GIFT   OF 


THE  PRESERVATION 

OF 

STRUCTURAL  TIMBER 


McGraw-Hill  DookCompany 


Electrical  World         The  Engineering  andMining  Journal 
En5ineering  Record  Engineering  News 

Kailway  Age  Gazette  American  Machinist 

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Electric  Railway  Journal  Coal  Age 

Metallurgical  and  Chemical  Engineering  P  o  we  r 


THE  PRESERVATION 


OF 
m 


STRUCTURAL  TIMBER 


BY 

HOWARD  F.  WEISS 
$ 

DIRECTOR,   FOREST   PRODUCTS   LABORATORY,    U.  S.  FOREST   SERVICE 
HONORARY    MEMBER,    AMERICAN   WOOD   PRESERVERS*   ASSOCIATION 


FIRST  EDITION 


McGRAW-HILL  BOOK  COMPANY,  INC. 
239  WEST  39TH  STREET,  NEW  YORK 

6  BOUVERIE  STREET,  LONDON,  E.  C. 

1915 


COPYRIGHT,  1914,  BY  THE 
MCGRAW-HILL  BOOK  COMPANY,  INC. 


THE. MAPLE. PRESS. YORK. PA 


FATHER  AND   MOTHER 
THIS  BOOK 

IS 
AFFECTIONATELY  DEDICATED 


PREFACE 

The  wood-preservation  industry  is  one  of  those  which  is  aid- 
ing in  the  great  movement  for  efficiency  in  operation  and  in  the 
the  conservation  of  our  natural  resources.  Practically  unknown 
in  our  country  but  a  half  century  ago,  its  growth,  especially  in 
the  last  decade,  has  been  exceedingly  rapid  until  there  are  now 
nearly  100  plants  in  operation  turning  out  over  125,000,000  cubic 
feet  of  treated  wood  annually.  Too  much  credit  for  this  splendid 
development  cannot  be  given  to  men  who  like  Dr.  Hermann  von 
Schrenk  have  by  their  ability,  knowledge,  and  persistence  brought 
the  importance  of  preserving  wood  to  the  attention  of  the  Ameri- 
can people  and  successfully  accomplished  a  mass  of  practical 
results.  There  is  every  reason  to  believe  that  the  growth  of  the 
industry  has  by  no  means  reached  its  climax,  for  there  are  thou- 
sands of  feet  of  structural  timber  used  each  year  that  are  not  being 
treated  but  which  should  and  eventually  will  be. 

In  an  industry  which  has  grown  so  rapidly  and  is  unique  in 
that  a  long  time  must  elapse  before  the  efficiency  of  many  of  its 
processes  are  known,  it  is  but  natural  that  many  perplexing  prob- 
lems should  arise.  The  wood  preservation  industry  certainly 
has  its  just  share  of  them,  and  although  splendid  progress  has 
been  made,  much  yet  remains  to  be  learned;  in  fact,  accurate 
knowledge  is  just  in  its  infancy.  The  whole  art  is  permeated  with 
contradictory  evidence  and  opinions  so  that  it  is  exceedingly 
difficult  for  the  layman  seeking  advice  to  become  other  than  con- 
fused. 

During  the  past  nine  years  it  has  been  my  good  fortune  to  be 
thrown  in  personal  contact  with  many  of  these  problems  and  to 
study  them  over  our  entire  country.  While  so  doing,  the  need 
for  a  book  on  the  subject  has  been  repeatedly  called  to  my  atten- 
tion, for  while  there  are  excellent  works  on  given  phases  of  wood 
preservation,  none  apparently  systematically  covers  the  subject 
in  its  broad  aspect.  It  has  been  necessary  to  consult  a  large 
number  of  separate  publications  to  secure  such  data — a  process 
most  tedious  and  unsatisfactory  in  this  day  of  straight-line  opera- 
tion. Furthermore,  it  is  thought  a  textbook  on  timber  preserva- 

vii 


viii  PREFACE 

tion  will  be  of  help  to  students  in  forestry  and  engineering  schools, 
where  a  knowledge  of  wood  utilization  is  desirable  and  often 
necessary. 

In  the  following  pages,  taken  largely  from  lecture  notes  pre- 
pared by  the  author  for  the  civil  engineering  students  at  the 
University  of  Wisconsin,  it  has  been  the  aim  to  present  reliable 
information  of  fundamental  importance.  It  is  hoped  that  they 
will  be  found  of  value  and  use  to  engineers,  foresters,  lumbermen, 
students  and  all  those  interested  in  this  subject  and  that  this 
effort  may  assist  in  raising  still  higher  the  enviable  position 
already  held  by  the  wood-preserving  industry. 

The  author  certainly  wishes  to  acknowledge  his  indebtedness 
to  the  U.  S.  Forest  Service,  from  the  publications  and  illustrations 
of  which  he  has  very  heavily  drawn;  to  his  friends  engaged  in 
commercially  treating  timber,  especially  Mr.  F.  J.  Angier,  Mr. 
Carl  G.  Crawford,  and  Mr.  J.  B.  Card,  whose  generous  assistance 
has  added  much  to  this  book;  and  to  various  associations  and 
societies  from  whose  proceedings  data  have  been  taken. 

H.  F.  W. 

MADISON,  WISCONSIN, 
October  1,  1914. 


CONTENTS 


PAGE 

PREFACE vii 

LIST  OF  PLATES  .  .    xiii 


CHAPTER  I 

INTRODUCTION 1 

Definition  of  wood  preservation — Importance  of  wood  preservation 
as  an  American  industry — Present  standing  of  the  wood  preserving 
industry  in  the  United  States — Conserving  our  timber  supply — 
Effect  of  wood  preservation  on  forest  management — History  of 
wood  preservation  in  Egypt,  Europe,  United  States. 

CHAPTER  II 

FACTORS  WHICH  CAUSE  THE  DETERIORATION  OF  STRUCTURAL  TIMBER.      15 
Discussion  of   their  relative  importance — Decay — Insects — The 
pole  borer — Marine  borers — Xylotrya,  Nausitoria  and  Teredo — 
The  Phola — Mechanical  abrasion — Fire — Minor  factors — Alkaline 
soils — Birds — Sap  stain. 

CHAPTER  III 

THE  EFFECT  OF  THE  STRUCTURE  OF  WOOD  UPON  ITS  INJECTION  WITH 

PRESERVATIVES 31 

Effect  of  density  upon  absorption — Absorption  by  the  cell  walls — 
The  effect  of  sapwood  and  heartwood  upon  injection — The  effect  of 
summerwood  and  springwood  upon  injection — The  effect  of  vessels 
or  "pores"  on  the  treatment  of  wood — The  effect  of  tyloses  on 
the  treatment  of  wood — The  effect  of  resin  ducts  on  the  treatment 
of  wood — The  effect  of  pits  upon  injection — The  effect  of  cell  slits 
upon  penetration — The  effect  of  the  chemical  composition  of  the 
cell  wall  upon  absorption. 

CHAPTER  IV 

THE  PREPARATION  OF  TIMBER  FOR  ITS   PRESERVATIVE  TREATMENT  .     40 
The  cutting  season — Peeling  timber — Seasoning  timber — Open-air 
seasoning — Hot-air  seasoning — Seasoning  in   saturated    steam — 
Seasoning  in  superheated  steam — Seasoning  in  oil — Soaking  timber 
in  water  preparatory  to  seasoning  it. 

ix 


X  CONTENTS 

CHAPTER  V 

PAGE 

PROCESSES  USED  IN   PROTECTING   WOOD   FROM   DECAY 50 

Superficial  processes — Charring — Brush  treatments — Dipping — 
Impregnation  processes — Non-pressure  processes — Kyanizing  proc- 
ess— Open-tank  processes — Seeley  process — Giussani  process — 
Pressure  processes — Bethell  (Full-cell  Creosote)  process — Boiling 
process — Buehler  process — A.  C.  W.  process — Lowry  process — 
Rueping  process — Burnett  process — Rutgers  process — Card  process 
— Wellhouse  process — Allardyce  process. 

CHAPTER  VI 

PRESERVATIVES  USED  IN  PROTECTING  WOOD  PROM  DECAY.  .  .  .  .  64 
Properties  of  efficient  preservatives — Water-soluble  preservatives 
— Copper  sulphate — Mercuric  chloride — Sodium  fluoride — Zinc 
chloride — Crude  oils — Creosotes — Coal-tar  creosote — Water-gas- 
tar  creosote — Wood-tar  creosote — Mixed  coal-tar  creosotes — 
Source  of  tars — Distillation  of  creosote  from  tars — Paints  and 
stains. 

CHAPTER  VII 

THE  CONSTRUCTION  AND  OPERATION  OF  WOOD  PRESERVING  PLANTS  .  .  89 
Open-tank  plants — Pressure  plants — The  retort  house — Retorts 
(cylinders) — Retort  thermometer — Retort  gauges — Anchors  and 
"turtles" — Retort  coils — Guard  rails — Retort  doors — Retort  lag- 
ging— The  pump  house  or  room — The  machine  shop  or  room — The 
boiler  house — Yard — Loading  dock — Methods  of  transferring 
material  in  the  yard — Cylinder  cars — Measuring,  mixing,  working, 
and  storage  tanks — Gauges  and  scales — Piping — Shower  baths — 
Inspector's  laboratory — Fire  protection — Lighting  equipment — 
Sawmill  and  block  equipment — Tie  boring  and  adzing  machines — 
The  operation  of  pressure  plants — The  effect  of  the  vacuum — The 
effect  of  air  pressure — The  effect  of  pressure  on  the  preservative — 
Some  common  errors  and  difficulties  in  operating  pressure  plants — 
Difficulty  of  measuring  volume  of  charge — Expansion  of  creosote — 
Expansion  of  cylinder — Compression  of  the  oil  and  wood — 
"Kickback "  of  preservative — Expansion  of  wood — Extent  of  possi- 
ble errors — Purity  of  the  preservative — Pollution  of  streams — 
Inspection  of  treatments — Cost  of  pressure  plants. 

CHAPTER  VIII 

PROLONGING  THE  LIFE  OF  CROSS  TIES  FROM  DECAY  AND  ABRASION.  .  128 
Selection  of  species — Hewed  versus  sawed  ties — Bearing  afforded 
tie-plates  and  rails — Uniformity  in  volume — Waste  of  material — 
Form  of  cross-ties — Stacking  ties  for  seasoning — Grouping  ties  to 
secure  uniform  treatment — Species  of  wood — Proportion  of  sap- 
wood — Moisture  content — Cutting  season — Conditions  of  growth 


CONTENTS  xi 

PAGE 

— Protection  from  abrasion — Tie-plates^-Spikes — Adzing  and 
boring  ties — The  selection  of  processes  for  treating  ties — Cost  of 
treating  ties — Economy  in  treating  ties — Need  for  test  tracks. 

k 

CHAPTER  IX 

PROLONGING  THE  LIFE  OP  POLES  AND  CROSS  ARMS  FROM  DECAY  AND 

INSECTS 156 

Poles — Selection  of  species — Manufacture  of  poles — Methods  of 
seasoning — Methods  of  treatment  and  their  selection — Setting  in 
crushed  stone  or  concrete — Charring — Brush  treatments — Open- 
tank  butt  treatments — Entire  impregnation — Boucherie  process — 
Kyan  process — Re-enforcing  decayed  poles — Cost  of  treatment — 
Economy  of  treatment.  Crosss  Arms — Selection  of  species — The 
manufacture  of  cross  arms — Methods  of  seasoning — Methods  of 
treatment  and  their  selection — Cost  of  treatment — Economy  of 
treatment. 

CHAPTER  X 

PROLONGING  THE  LIFE  OF  FENCE  POSTS  FROM  DECAY 172 

Selection  of  species — Method  and  time  of  cutting  posts — Method  of 
seasoning — Methods  of  treatment  and  their  selection — Setting 
posts  in  stones — Setting  posts  upside  down — Charring  the  butt — 
Dipping  in  crude  oil  and  charring — Diagonal  holes  filled  with  pre- 
servative— Brush  treatments — Dipping  treatments — Impregnation 
treatments — Pitch  streaks — Cost  of  treatment — Economy  of  treat- 
ment. 

CHAPTER  XI 

PROLONGING  THE  LIFE  OF  PILING  AND  BOATS  FROM  DECAY  AND  MARINE 

BORERS 181 

Selection  of  species — The  manufacture  of  piling — Methods  of 
seasoning — Methods  of  treatment  and  their  selection — Bark  left  on 
piles — Plank  coating — Nail  coating — Metal  coating — Burlap  coat- 
ings— Cement  casings — Electrolysis — Impregnation  with  coal-tar 
creosote — Cost  of  treating  piling — Economy  of  treatments — The 
preservative  treatment  of  wooden  boats. 

CHAPTER  XII 

PROLONGING  THE  LIFE  OF  MINE  TIMBERS 18'8 

Selection  of  species — The  manufacture  of  mine  timbers — Methods 
of  seasoning — Methods  of  treatment  and  their  selection,  mine  ties, 
mine  props,  square  sets,  lagging — The  treatment  of  mine  timbers  in 
relation  to  fire — Cost  of  treatments — Economy  of  treatments. 


xii  CONTENTS 

CHAPTER  XIII 

PAGE 

PROLONGING  THE  LIFE  OF  PAVING  BLOCKS 195 

Progress  of  wood  paving — Selection  of  species — The  manufacture 
of  paving  blocks — Methods  of  treatment — Troubles  experienced 
with  wood  block  paving — Slipperiness — Exudation  of  oil — Ex- 
pansion of  the  blocks — Method  of  laying  wood  blocks — Cost  of 
treatment — Advantages  of  wood  block  pavements — Wood  blocks 
for  barns,  factories,  etc. 

CHAPTER  XIV 

PROLONGING  THE  LIFE  OF  SHINGLES 205 

Selection  of  species — Methods  of  treating  shingles,  against  decay, 
against  fire — Cost  of  treating  shingles. 

CHAPTER  XV 

PROLONGING  THE  LIFE  OF  LUMBER  AND  LOGS 205 

Methods  of  treating  lumber  for  rough  construction — Methods  of 
treating  lumber  for  buildings,  greenhouses  and  cars — Methods  of 
preserving  logs  from  decay — Methods  of  treating  log  cabins  and 
rustic  furniture. 

CHAPTER  XVI 

THE  PROTECTION  OF  TIMBER  FROM  FIRE 213 

The  theory  of  rendering  wood  fire  retardant — Superficial  processes 
— Impregnation  processes — Chemicals  used — Commercial  treat- 
ment— Tests  to  determine  the  inflammability  of  timber:  shaving 
test,  crib  test,  spot  test,  electric  furnace — Cost  of  rendering  wood 
non-combustible — The  effect  of  zinc  chloride  and  creosote  on  the 
inflammability  of  wood. 

CHAPTER  XVII 

THE  PROTECTION  OF  WOOD  FROM  MINOR  DESTRUCTIVE  AGENTS    .    .221 
Alkaline  soils — Birds — Sap  stain — Sand  storms. 

CHAPTER  XVIII 

THE  STRENGTH  AND  ELECTROLYSIS  OF  TREATED  TIMBER 224 

The  effect  of  air  seasoning  on  the  strength  of  wood — The  effect  of 
steaming  on  the  strength  of  wood — The  effect  of  boiling  wood  in 
creosote  upon  its  strength — The  effect  of  preservatives  on  the 
strength  of  wood,  creosote,  zinc  chloride,  crude  oil — The  effect  of 
temperature  on  the  strength  of  wood — The  effect  of  pressure  on  the 
strength  of  wood — The  effect  of  various  treatments  on  the  strength 
of  wood — The  electrical  resistance  of  wood  treated  with  creosote 
and  zinc  chloride. 


CONTENTS  xiii 

CHAPTER  XIX 

PAGE 

THE  USE  OF  SUBSTITUTES  FOR  TREATED  TIMBER 243 

Substitutes  for  wood  ties— S&bstitutes  for  wood  poles — Substitutes 
for  wood  piling — Substitutes  for  wood  posts — Substitutes  for  wood 
mine  timbers — Substitutes  f^Jr  wood  bridges — Substitute  for  woo  1 
in  buildings  and  cars — Substitutes  for  wood  hingles — Substitutes 
for  wood  conduits  and  pipes. 

CHAPTER  XX 

APPENDICES 249 

Minor  wood  preserving  processes — Thilmany  process,  B-M  process, 
Goltra  process,  Hasselmann  process,  Creo-resinate  process  Robbins 
process,  Powell  process,  Creoaire  process,  Vulcanizing  process, 
Cresol-calcium  process. 

Patented,  proprietary,  and  minor  wood  preservatives  used  in  the 
United  States — Cresol  calcium,  S.  P.  F.  Carbolineum,  Avenarius 
Carbolineum,  C.  A.  Wood  Preserver,  Timberasphalt,  Preservol, 
Copperized  oil,  sodium  silicate,  Spirittine,  B.  M.  Preservative, 
water-gas-tar  creosote,  Holzhelfer,  wood  creosote,  sodium  fluoride, 
Aczol,  Sapwood  Antiseptic,  N.  S.  Special,  Imperial  Wood  Pre- 
servative, Kreodone,  Locustine,  Creoline. 

List  of  manufacturers  of  zinc  chloride  in  the  United  States — List 
of  manufacturers  of  creosote  in  the  United  States — List  of  wood 
preserving  plants  in  the  United  States — List  of  fireproofing  plants 
in  the  United  States — The  amount  of  wood  preservatives  used  in 
the  United  States — The  amount  of  timber  treated  in  the  United 
States — List  of  companies  in  the  United  States  equipped  to  build 
wood-preserving  plants — Specifications  for  the  analysis  of  creosote 
adopted  by,  the  American  Railway  Engineering  Association,  the 
National  Electric  Light  Association,  the  United  States  Forest  Serv- 
ice— Method  for  determining  the  amount  of  moisture  in  creosote 
and  creosoted  wood — The  durability  of  American';  timbers — List  of 
U.  S.  patents  in  wood  preservation — Method  of  analyzing  zinc 
chloride — Records  on  the  life  of  timbers,  mine  timbers,  paving 
blocks,  poles,  cross-ties. 

INDEX.  .  305 


LIST  'OJ  PLATES 


Frontispiece. — Wood    Preservation    Section    of    the    Forest    Products 

Laboratory  maintained  by  the  U.  S.  Forest  Service  in  co-operation 

with  the  University  of  Wisconsin,  Madison,  Wis Frontis. 

FACING  PAGE 

PLATE  I 8-9 

Fig.  A. — A  stand  of  young  lodgepole  pine  in  Idaho. 

Fig.  B. — Egyptian  coffin  dating  from  the  XII  dynasty  (2000-1788 

B.  C.).     The  only  restorations  are  three  cleats  on  the  bottom  of  the 

coffin,  otherwise  it  is  in  almost  perfect  preservation. 
Fig.  C. — Lentinus  lepidens. 
Fig.  D. — Lenizites  sepiaria. 

PLATE  II ' 18-19 

Fig.  A. — A  red   oak    tie    attacked   by    a   wood    destroying   fungus 

(Stereum  fasciatum,  Schw.). 
Fig.  B. — (1)  The  pole  borer:  male  and  female  beetles.     (2)  Young 

larvae. 

Fig.  C. — Gallery  of  the  pole  borer. 
Fig.  D. — Mines  of  the  pole  borer  near  the  surface  of  the  ground. 

PLATE  III 26-27 

Fig.  A. — Cedar  ties  badly  damaged  by  rail  cutting.     Upper  section 

shows  tie  without  plate,  lower  section  shows  tie  plate  was  too  small. 
Fig.  B. — Poles  destroyed  by  a  sleet  storm  in  Maryland,  1904. 
Fig.  C. — Results  of  a  fire  at  the  Arlington  Manufacturing  Company's 

mill,   Arlington,    N.    J.     In  rebuilding,   wood  beams  were  used 

throughout. 

PLATE  IV 34-35 

Fig.  A. — Longleaf  pine  boards  piled  solidly  after  one  month's  ex- 
posure to  sap  stain  fungi.     Boards  on  left,  untreated;  boards  on 

right  dipped  in  a  weak  solution  of  mercuric  chloride.     Note  absence 

of  stain. 
Fig.  B. — Cross  section  through    red    oak — a  "ring  porous"  wood. 

Note  arrangement  of  pores  mostly  in  the  spring  wood.     Note  also 

clearness  of  pores.      X50. 
Fig.   C. — Cross-section  through  maple — a  "diffuse  porous"  wood. 

Note  pores  scattered  through  entire  width  of  annual  ring.      X50. 
Fig.  D. — Cross-section    through    spruce — a    "non-porous"    wood. 

Note  absence  of  pores.     Larger  openings  are  "resin  ducts"  or  cells. 

X50. 
Fig.  E. — Cross-section  through  white  oak.     Note  pores  clogged  with 

"Tyloses."     Compare  with  red  oak.     X50. 
Fig.  F. — Radial  section  through  pine.     Note  bordered  pits  or  "eyes," 

also  how  fibers  fit  into  one  another.     Vertical  cells  on  extreme  left 

are  medullary  or  "pith  ray"  cells.     X250. 

xv 


xvi  LIST  OF  PLATES 

FACING  PAGE 
PLATE  V 36-37 

Fig.  A. — Cross-section  through  a  loblolly  pine  tie.  Note  wide  rings 
showing  rapid  growth,  also  note  sharp  transition  of  spring  wood 
and  summerwood. 

Fig.  B. — Cross-sections  through  two  longleaf  pine  stringers.  Note 
narrow  rings  especially  in  sapwood,  showing  slow  growth. 

Fig.  C. — Cross-section  through  the  summerwood  of  larch  (greatly 
magnified)  showing  slits  in  cell  walls. 

Fig.  D. — Showing  ease  with  which  chestnut  peels  in  the  spring. 
PLATE  VI 52-53 

Fig.  A. — Sections  of  creosoted  piling  showing  effect  of  thin  strips  of 
bark  adhering  to  the  wood. 

Fig.  B. — Brush  treating  poles. 

Fig.  C. — An  open  tank  plant  for  treating  the  butts  of  poles — Cali- 
fornia. 

Fig.  D. — Wood  preserving  plant  of  the  C.  B.  &  Q.  R.  R.,  Galesburg, 

111. 
PLATE  VII 90-91 

Fig.  A. — A  post  treating  plant  made  of  two  barrels  and  an  iron  pipe. 

Fig.  B. — An  open  tank  post  treating  plant — California. 

Fig.  C. — An  open  tank  post  treating  plant.  Note  heat  is  furnished 
by  steam  from  threshing  engine.  Small  cylindrical  tank  is  for  butt 
treating  in  a  hot  bath;  rectangular  tank  is  for  a  cold  bath. 

Fig.  D. — Open  tank  wood  preserving  plant  for  ties.     The  ties  are  car- 
ried through  the  plant  on  an  endless  chain. 
PLATE  VIII 92-93 

Fig.  A. — Small  wood  preserving  plant  designed  by  the  U.  S.  Forest 
Service  in  co-operation  with  the  Louisiana  Creosoting  Co. 

Fig.  B. — View  through  a  large  treating  cylinder.  Note  guard  rails, 
steam  coils  and  track.  International  Creosoting  and  Construction 
Company 

Fig.  C. — Spider  door  with  independent  sockets. 

Fig.  D. — Spider  door  with  continuous  socket  support. 

Fig.  E. — Construction  of  a  cast  steel  door. 
PLATE  IX 96-97 

Fig.  A. — The  construction  of  the  collar  and  door  in  a  pressure  cylin- 
der. Note  cylinder  track  and  guard  rails. 

Fig.  B. — Construction  of  a  door  with  cast  steel  rim  and  dished  plate 
steel  head. 

Fig.  C. — Cylinder  doors  without  hinges.  Norfolk  Creosoting  Com- 
pany. 

Fig.  D. — Pump   room    C.    B.    &   Q.    R.    R.    treating  plant.     Note 

arrangement  of  gauges  and  control  valves. 
PLATE  X 100-101 

Fig.  A. — Chicago  &  Northwestern  tie  treating  plant,  Escanaba, 

Mich. 

.  Fig.  B. — Tie  treating  plant  of  the  Pennsylvania  R.  R.  Note  con- 
crete loading  dock  with  empty  cylinder  cars  on  top  also  manner  of 
unloading  and  piling  ties  for  air  seasoning. 


LIST  OF  PLATES  xvii 

FACING  PAGE 

Fig.  C. — Unloading  treated  ties  from  cylinder  buggies  into  gondolas 
with  a  locomotive  crane.     Port  Reading  Creosoting  Company. 

Fig.  D. — Overhead  electric  crane  foHoading  timber  into  cylinder  cars. 

Gulfport  Creosoting  Co.,  Gulfport,  Miss. 
PLATE  XI ^ 102-103 

Fig.  A. — Bolster  car.     Us*ed  for  long  timbers. 

Fig.  B. — A  tie  car. 

Fig.  C. — Mercury  gauge  for  measuring  the  preservative  in  the  meas- 
uring tank.     Baltimore  &  Ohio  R.  R.  tie  plant. 

Fig.  D. — Wood  block  treating  plant  of  the  Chicago  Creosoting  Co., 

Terre  Haute,  Ind.     Note  vertical  cylinders. 
PLATE  XII 106-107 

Fig.  A. — Ties  entering  boring  and  adzing  machine. 

Fig.  B. — Ties  adzed  and  bored  being  piled  on  the  cylinder  cars  ready 
for  treatment. 

Fig.  C. — Section  through  an  oak  tie  showing  a  cut  and  screw  spike 

driven  in  place.     Note  comparative  distortion  of  wood  fibers. 
PLATE  XIII 132-133 

Fig.  A. — Method  of  hewing  oak  ties  in  Tennessee.     Note  waste. 

Fig.  B. — Rectangular  cross  ties — Standard  form  in  the  United  States. 

Fig.  C. — Standard  Prussian  ties  of  Baltic  pine. 

Fig.  D. — Triangular  cross  ties — Great  Northern  Ry. 
PLATE  XIV 142-143 

Fig.  A. — A  good  method  of  piling  ties  for  air  seasoning.     Port  Read- 
ing Creosoting  Co. 

Fig.  B. — White  oak  ties  seasoned  to  fast. 

Fig.  C. — Ties  "protected"  with  wooden  plates.     Note  plate  crushed 
into  tie. 

Fig.  D.— Metal  tie  plate. 
PLATE  XV 158-159 

Fig.  A. — Cedar  poles  piled  for  storage — Michigan. 

Fig.  B. — Poles    properly    piled    for    air    seasoning — Black    Forest, 
Germany. 

Fig.  C. — An  open  tank  pole  treating  plant.     A  poor  design;  note 
creosote  evaporating  from  tanks. 

Fig.  D. — Creosoted  poles  for  heavy  construction — Hayes,  England. 
PLATE  XVI 164-165 

Fig.  A. — A  boucherie  pole  treating  plant — Fulda,  Germany. 

Fig.  B. — Partially  decayed  pole  reinforced  with  a  creosoted  stub. 

Fig.  C. — Method  of  reinforcing  a  partially  decayed  pole  with  a  con- 
crete jacket. 
PLATE  XVII 170-171 

Fig.  A. — Cross  arms  properly  piled  for  air  seasoning. 

Fig.  B. — Creosoted  cross  arms  just  leaving  the  treating  cylinder. 
Norfolk  Creosoting  Co. 

Fig.  C. — Fence  posts  properly  piled  for  air  seasoning. 

Fig.  D. — Untreated  lodgepole  pine  post  set  4  years.     Note  decay  at 
the  ground. 


xviii  LIST  OF  PLATES 

FACING  PAGE 

PLATE  XVIII 182-183 

Fig.  A. — Fence  posts  dipped  in  crude  oil  and  then  charred.     Note 

good  condition  after  12  years  service. 
Fig.  B. — Sections  of  creosoted  piling.     Note  erratic  penetrations  of 

creosote. 
Pig.  C. — Pile  sheathed  with  zinc  entirely  destroyed  by  marine  borers 

— Pensacola,  Fla. 
Fig.  D. — Piling  protected  with  cement  casings  from  attack  by  marine 

borers — Pensacola,  Fla. 

PLATE  XIX 186-187 

Fig.  A. — Sections  of  longleaf  pine  piles  after  21  months'  exposure  to 

the  attack  of  marine  borers  at  Gulfport,  Miss.     Section  to   the 

right,  untreated;  section  to  the  left  impregnated  with  a  crude  oil. 
Fig.  B. — Untreated  pine  piles  completely  destroyed  by  marine  wood 

borers — Santa  Rosa  Island,  Fla. 

PLATE  XX   . 192-193 

Fig.  A. — Gangway  of  treated  mine  timbers — Pottsville,  Pa. 

Fig.  B. — Rank  growth  of  fungus  on  mine  timbers. 

Fig.  C. — Treated  and  untreated  mine  props.     Treated  prop  to  right 

set  at  same  time  as  failed  untreated  prop  at  left — Pennsylvania. 
Fig.  D. — Untreated  mine  props  destroyed  by  decay  and   "squeeze," 

— Pennsylvania. 

PLATE  XXI 202-203 

Fig.  A. — A  "popup  "  or  failure  in  a  street  laid  with  creosoted  blocks 

due  to  their  expansion. 

Fig.  B. — Wood  block  pavements — grading  the  sand  cushion  and  lay- 
ing the  blocks — Minneapolis,  Minn. 
Fig.  C. — Working  the  tar  filler  into  the  joints  of  a  newly  laid  wood 

block  pavement. 
Fig.  D. — Pine  beams  in  a  building  completely  rotted  in  the  ends  after 

30  years  service — Madison,  Wis. 

PLATE  XXII 224-225 

Fig.  A. — Type  of  soda  dipping  tank  manufactured  by  the  Lufkin 

Foundry  &  Machine  Co. 
Fig.  B. — Stake  damaged  by  sand  storms  in  southern   California. 

Compare  portion  in  the  ground  with  portion  above  ground. 
Fig.  C. — Section  of  an  experimental  track  laid  with  steel  ties. 
Fig.  D. — A  fence  of  concrete  posts — Madison,  Wis. 

PLATE  XXIII 246-247 

Fig.  A. — Concrete  mine  props — Pennsylvania. 

Fig.  B. — Indiana  Tie  Company's  wood  preserving  plant,  Joppa,  111. 

Note  depressed  tracks  and  manner  of  running  cylinder  cars    on 

flat  cars  for  loading  ties  into  box  cars  for  shipment. 
Fig.  C. — Nest  box  used  to  protect  poles  and  buildings  from  attack 

by  wood  peckers. 
Fig.  D. — Wood  dowels  screwed  into  soft-wood  ties  as  a  protection 

against  spike  cutting. 


THE  PRESERVATION 
OF  STRUCTURAL   TIMBER 

CHAPTER  I 
INTRODUCTION 

Definition  of  Wood  Preservation. — Wood  preservation  may  be 
defined  as  the  art  of  protecting  structural  timber  from  decay. 
This  is  the  common  acceptance  of  the  term.  When  considered 
in  its  broadest  aspect,  however,  it  includes  much  more  than  this, 
since  decay  is  but  one  factor  causing  the  destruction  of  wood.  It 
is  in  its  broadest  sense  that  the  subject  is  discussed  in  this  treatise, 
because  it  is  believed  that  the  practice  of  protecting  from  deteri- 
oration will  broaden  as  wood  increases  in  value. 

In  order  to  adequately  treat  the  subject,  wood  preservation 
will  be  defined  as  the  art  of  protecting  structural  timber  from 
deterioration  by  destructive  agents.  The  more  common  of  these 
are  decay,  insects,  marine  borers,  mechanical  abrasion,  and  fire. 
It  should  be  noted  that  the  definition  does  not  include  the  pro- 
tection of  trees,  as  the  methods  of  doing  this  are  entirely  distinct 
from  those  practised  in  protecting  wood  cut  from  the  trees  after 
they  have  been  felled.  This  distinction  should  be  kept  clearly 
in  mind. 

Importance  of  Wood  Preservation  as  an  American  Industry. — 
In  an  undeveloped  country  destined  for  civilization  extensive 
forests  are  an  obstruction  which  must  be  removed,  because  they 
occupy  land  needed  for  agriculture.  As  long  as  a  country  is 
heavily  timbered,  conservative  methods  of  utilizing  the  timber 
will  rarely  be  practised.  This  condition  prevailed  in  the  United 
States  during  its  early  history  but  exists  no  longer.  Scientific 
methods  of  managing  forests  as  well  as  efficient  methods  of  utiliz- 
ing the  timber  cut  from  them,  are  now  being  practised.  Both, 
however,  are  still  in  their  infancy  but  they  are  undergoing  a  rapid 
application.  These  economic  changes  are  excellently  reflected 
in  the  United  States  in  the  development  of  the  wood  preserving 
industry. 

1 


2  THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Present  Standing  of  the  Wood  Preserving  Industry  in  the 
United  States. — There  are  now  about  90  wood  preserving  plants 
in  active  operation  in  the  United  States  representing  a  capitali- 
zation of  over  $10,000,000  and  turning  out  products  worth  about 
$30,000,000  per  year.  These  plants  use  annually  over  100,000,000 
gallons  of  creosote  costing  over  $7,000,000  and  over  21,000,000 
pounds  of  zinc  chloride  costing  about  $1,000,000.  In  addition, 
about  3,500,000  gallons  of  various  other  preservatives  are  annu- 
ally consumed  representing  a  value  of  perhaps  $1,250,000.  The 
total  amount  of  wood  treated  approximates  126,000,000  cubic 
feet  per  year,  which  is  equivalent  to  the  amount  of  wood  produced 
annually  by  about  10,000,000  acres  of  average  American  forest. 
Since  present  methods  of  lumbering  waste  about  50  percent  of 
the  wood  grown,  the  amount  of  wood  now  annually  treated  repre- 
sents a  protection  given  to  the  annual  output  of  approximately 
20,000,000  acres  of  timberland. 

To  the  above  should  be  added  several  millions  of  dollars  spent 
each  year  in  protecting  timber  from  mechanical  destruction  and 
about  a  quarter  of  a  million  protecting  wood  against  fire. 

Conserving  our  Timber  Supply. — A  natural  result  of  the  in- 
creasing practice  of  preserving  wood  is  to  decrease  the  drain  on 
our  forests  and  hence  help  to  conserve  our  supply  of  timber. 
This  is  offset  in  part  by  the  growth  of  the  country,  demanding 
more  raw  materials,  so  that  no  accurate  estimate  on  the  extent  to 
which  wood  preservation  will  ultimately  decrease  the  demand 
for  structural  timber  to  be  used  for  replacements  can  be  given. 
The  author  attempted  such  an  estimate  in  1909  for  the  National 
Conservation  Commission.  Certain  modifications  now  appear 
advisable,  although  the  estimate  as  then  given  has  not  been  ma- 
terially changed.  This  revised  estimate  is  given  in  Table  1.  It 
attempts  to  show  to  what  extent  the  demand  on  our  forests  can 
be  decreased  if  all  timber  placed  in  situations  where  it  is  liable  to 
deterioration  were  treated  in  some  approved  manner.  For  ex- 
ample, we  now  use  each  year  about  100,000,000  cross-ties  to  re- 
place those  which  have  worn  out  through  decay,  wear,  and  other 
causes.  If  these  ties  were  given  an  efficient  preservative  treat- 
ment, their  life  could  be  prolonged  and  in  a  few  years  the  demand 
for  ties  would  decrease  to  about  42,000,000  annually  instead  of 
100,000,000  as  at  present.  Of  course  this  neglects  the  ever  in- 
creasing demand  for  ties  due  to  new  construction.  Estimating 
along  these  lines,  it  appears  that  the  application  of  efficient  pro- 


INTRODUCTION  3 

tective  measures  to  structural  timber  would  decrease  the  drain 
on  our  forests  by  almost  7,000,000,000  board  feet  annually,  were 
all  such  timber  which  is  liable  tq  deterioration  protected. 

k 

TABLE  1. — ESTIMATED  DECREASE  L*  THE  ANNUAL  CUT  OF  TIMBER  WHICH 

WOULD  RESULT* WERE  ALL  TIMBER  WHICH  is  SUBJECT 

TO  DETERIORATION  PROPERLY  PROTECTED 


Class 

Estimated  average 
life  in  years 

Estimated  annual 
replacements 

Estimated 
saving      in 
annual  cut 
resulting 
from  proper 
protection 
(number) 

Total 
annual 
saving 
(M  B  M) 

Untreated 

Treated 

Untreated 
(number) 

Treated 
(number) 

Ties  

7 

17 

100,000,000 

41,200,000 

58,800,000 

2,000,000 

Poles  

13 

26 

2,500,000 

1,250,000 

1,250,000 

150,000 

Posts  

8 

24 

500,000,000 

165,000,000 

335,000,000 

2,000,000 

Piling  

3 

20 

1,000,000 

150,000 

850,000 

100,000 

Mine  props. 

3 

15 

70,000,000° 

14,000,000° 

56,000,000" 

275,000 

Shingles..  .  . 

20 

35 

1,000& 

600b 

4006 

400 

Lumber.  .  .  . 

8 

20 

3,000,0006 

l,200,000b 

1,800,000& 

1,800,000 

Total  

6,725,000 

a  =  cubic  feet.    6  =  MBM. 

That  this  shrinkage  in  the  amount  of  timber  cut  from  forests 
due  to  the  extended  use  of  preservative  treatment  is  not  only  a 
logical  but  a  real  outgrowth  is  shown  in  part  by  the  experience  of 
France.  Although  the  French  forests  have  been  severely  culled, 
they  still  furnish  about  3,000,000  ties  annually.  Approximately 
2,500,000  are  used  each  year  for  renewals,  which  number  has  been 
steadily  diminishing  in  spite  of  the  fact  that  the  total  mileage  of 
the  country  has  been  increasing.1  The  practice  of  preservative 
treatment  in  our  country  has  been  too  recent  to  make  its  influence 
on  forest  demands  as  yet  apparent  but  that  similar  results  will  be 
experienced  cannot  be  doubted. 

Effect  of  Wood  Preservation  on  Forest  Management. — En- 
tirely apart  from  the  problem  of  husbanding  our  forest  resources 
is  the  effect  of  treating  timber  on  the  practice  of  managing  our 
forests.  By  giving  durability  to  woods  which  do  not  naturally 
possess  it,  the  practice  of  wood  preservation  will  in  many  cases 


1  H.  Matheiu,  Revue  Ge"n£rale  des  Chemins  de  Fer,  August,  1887. 


4  THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

govern  the  manner  in  which  certain  forests  will  be  composed  and 
managed. 

Forestry  teaches  that  trees  grow  according  to  defined  onto-  and 
phylogeneric  laws,  like  all  other  forms  of  life,  and  if  these  laws 
are  violated,  destruction  will  inevitably  follow.  A  layman,  for 
example,  may  not  understand  why  a  young  tulip  tree  will  not 
grow  in  his  dense  maple  grove. 

The  utilization  of  various  kinds  of  timber  has  shown  that  some 
combine  more  valuable  properties  for  man's  purposes  than 
others.  A  study  of  these  properties  has  been  brought  about 
chiefly  through  dire  necessity.  Starting  with  the  cream,  man 
has  been  forced  to  the  milk.  The  gums,  for  instance,  classed  as 
"tree  weeds"  a  few  years  ago,  are  now  eagerly  sought  and  util- 
ized. As  a  result  of  these  two  conditions,  namely,  the  knowledge 
of  the  laws  of  tree  growth  and  the  inherent  superiority  of  certain 
woods  for  commercial  purposes,  selected  types  of  forests  have  been 
evolved.  In  other  words,  man  endeavors  to  eliminate  the  unde- 
sirable species  and  foster  the  growth  of  those  best  fitted  to  his 
needs.  The  mixed  pine  and  beech  forests  of  Germany  may  be 
cited  as  an  illustration.  We  have  not  reached  this  stage  in  the 
United  States,  but  with  the  ever  increasing  intensity  of  forest 
management,  nature's  combinations  will  be  eradicated,  and  in 
their  place  will  be  developed  man's  idea  of  the  Society  of  the  Se- 
lect. Nature's  law  which  decrees,  "Since  no  two  organisms  are 
alike,  one  must  be  better  adapted  to  its  surroundings  than  the 
other,  and  the  less  adapted  must  sooner  or  later  perish,"  will  be 
changed  to  read:  "Since  no  two  organisms  are  alike,  one  must  be 
better  adapted  to  man's  needs  than  the  other,  and  the  less  adapted 
must  sooner  or  later  perish."  This  is  an  illustration  from  Forest 
Ecology,  which  depicts  man's  disturbing  influence  in  modifying 
various  forms  of  life  to  best  meet  his  requirements.  Thus  the 
American  forest  of  the  future  will  be  radically  different  in  kind  as 
well  as  in  degree  from  those  now  existing.  Of  the  forty  odd 
species  of  commercial  trees  now  found  in  the  Appalachians,  it  is 
safe  to  state  that  not  more  than  one-fourth  will  persist.  Certain 
trees,  like  the  hemlock,  will  become  commercially  extinct,  simply 
because  it  will  not  pay  to  grow  them.  This  is  not  a  view  into 
the  distant  future;  the  careful  selection  of  species  is  already 
common  practice  in  Europe,  and  even  now  is  being  actively 
applied  in  our  country. 

As  stated,   the   commercial  extinction  of  certain  American 


INTRODUCTION  5 

trees  and  the    restriction  of  others  is  inevitable,  and   will  be 
brought    about   because   they   lack   certain    specific    qualities. 

These  are  of  two  kinds: 

t 

1.  Sylvical — the  abundance  and  vitality  of  the  seed;  the  re- 
sistance of  the  young  ^plants  to  insects,  fire,  and  animals;  their 
adaptability  to  their  environment;  their  rate  of  growth,  etc.,  and 

2.  Commercial — the  size,  strength,  weight  and  beauty  of  the 
wood,  its  ease  of  workmanship,  and  its  durability. 

Of  all  these  properties,  durability  is  one  of  great  practical  mo- 
ment and  of  direct  bearing  on  this  treatise.  No  method  is 
known  whereby  all  kinds  of  wood  can  be  satisfactorily  treated 
with  preservatives.  Fortunately,  however,  the  species  best 
adapted  to  treatment  are  among  the  most  abundant,  and  possess 
certain  sylvical  and  commercial  properties  which  give  them  a 
decided  advantage  over  others.  These  properties  briefly  are: 
The  vitality  and  prolificacy  of  the  seed,  rapidity  of  growth,  and 
high  percentage  of  sapwood.  The  following  species  may  be 
classed  in  this  group:  Bull,  lodgepole,  loblolly,  shortleaf,  jack 
and  scrub  pines;  cottonwood,  red  and  scarlet  oaks,  silver  and  red 
maples;  white  birch;  buckeye;  black  and  cotton  gums.  All  of 
these,  with  the  possible  exception  of  the  bull  and  shortleaf  pines 
and  cottonwood,  are  commonly  classed  as  "inferior"  species. 
When  a  timbered  area  is  cut  or  burned  over,  these  are  the  com- 
mercial species  which  usually  first  come  in  to  reforest  it.  It 
should  be  noted  that  their  rate  of  growth  soon  culminates.  None 
of  them  are  long  lived,  and  none  of  them  have  durable 'wood. 
The  inherent  characteristics  of  these  trees  are  such  as  to  render  a 
forest  composed  of  them  easy  to  propagate  and  manage. 

Wood  preservation  thus  affects  the  composition  of  certain 
forests  as  the  forests  of  the  future  will  be  grown  for  specific  pur- 
poses. White  oak  will  be  as  rarely  used  for  cross-ties  as  black 
walnut  now  is  for  fence  rails.  Future  stands  of  timber  will  often 
be  composed  of  those  species  whose  wood  without  the  application 
of  a  chemical  treatment  would  have  such  a  limited  demand  that 
they  could  not  be  grown  at  a  profit. 

Suppose  that  an  individual  or  company  has  a  tract  of  denuded 
land  upon  which  it  is  decided  to  grow  timber.  Should  slow  or 
rapid  growing  species  be  planted?  Which  will  pay  better?  Al- 
most invariably  the  wood  of  the  former  is  more  durable  than 
that  of  the  latter,  but  if  figured  on  the  basis  of  annual  financial 
profit,  the  advantages  are  usually  in  favor  of  the  latter.  An 


6  THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

example  may  be  cited:  Loblolly  pine  in  an  index  stand  on  a  70- 
year  rotation  will  yield  about  33,000  feet  B.M.  per  acre;  longleaf 
pine  under  similar  conditions,  on  a  120-year  rotation,  will  yield 
about  25,000  feet  B.M.  Assuming  the  value  of  the  land  and  the 
cost  of  planting  at  $10  per  acre,  taxes  3  cents,  fire  protection 
and  management  2  cents  per  year,  and  interest  4  percent, 
the  total  cost  of  growing  the  loblolly  at  the  felling  period  will  be 
$174  and  the  longleaf  $1244  per  acre.  The  future  stumpage 
price  of  these  species  can  only  be  predicted,  but  at  the  time  the 
trees  were  cut,  suppose  the  value  to  be  $8  per  thousand  feet  B.M. 
for  loblolly  and  $13  for  longleaf,  or  an  advance  in  present  prices 
of  over  300  percent  for  loblolly  and  400  percent  for  longleaf. 
The  value  of  the  crops  per  acre  will  then  be  respectively  $264 
and  $325,  or  a  total  profit  of  $90  for  the  loblolly  and  a  deficit  of 
$919  for  the  longleaf.  Longleaf,  in  order  to  produce  a  profit 
equal  to  the  loblolly,  would  have  to  be  worth  about  $54  per 
thousand  feet  stumpage.  At  such  a  price  it  would  be  commerci- 
ally prohibitive.  In  other  words,  longleaf  pine  can  be  grown  only 
at  a  loss. 

In  order  to  take  a  most  favorable  view  of  a  question  like  the 
above,  let  us  assume  that  the  land  is  worth  only  $1  an  acre  and 
that  the  same  yield  will  be  obtained  by  natural  reforestation. 
Hence,  there  will  be  no  cost  for  planting.  Moreover,  we  will 
assume  no  charge  for  protection.  The  cost  of  the  crops  per  acre 
will  then  be  $26.50  for  loblolly  and  $192.90  for  longleaf,  or  net 
profit^  respectively  of  $237  and  $132  with  an  excess  of  $105  per 
acre  for  loblolly  pine.  Similar  examples  would  be  found  to  exist 
if  other  of  our  slow  growing  and  more  durable  woods  were  com- 
pared with  those  listed  in  the  so-called  " inferior"  group. 

Exceptions,  of  course,  occur,  notably  with  such  species  as 
black  locust,  catalpa,  osage  orange,  chestnut,  and  eucalypts, 
which  combine  durability  with  rapidity  of  growth.  But  these 
trees  are  of  small  size  or  poor  form  or  are  subject  to  insect  or 
fungus  attack  or  are  decidedly  limited  in  distribution.  Whenever 
these  species  can  be  profitably  grown  their  extension  should  by  all 
means  be  encouraged,  because  they  combine  many  of  those  quali- 
ties in  strong  demand  and  their  subsequent  treatment  with 
preservatives  is  not  a  necessity.  That  the  use  to  which  its 
products  will  be  put  often  controls  the  composition  of  a  forest  is 
further  shown  in  this  country  by  the  plantations  of  various  rail- 
roads. The  Pennsylvania,  for  example,  has  planted  large  areas 


INTRODUCTION  7 

to  so-called  " treatment  woods/'  such  as  red  oak  in  place  of  the 
slower  growing  white  oak  and  other  more  durable  woods  mentioned 
above.  The  U.  S.  Forest  Service  is  managing  certain  of  its 
lodgepole  pine  forests  for  the  direct  purpose  of  producing  cross- 
ties.  Without  preserration,  it  would  not  pay  to  use  this  pine  for 
ties  because  of  its  rapid  decay.  (See  Plate  I,  Fig.  A.) 

Wood  preservation  enables  trees  removed  in  thinning  the  forest 
to  be  put  to  a  higher  use  than  for  fuel  and  by  so  doing  permits 
thinnings  to  be  more  systematically  and  effectively  made. 
If  a  forest  plantation  is  started  with  1200  trees  to  the  acre,  it  is 
safe  to  assume  that  not  more  than  17  percent — or  a  total  of  204 — 
will  remain  for  the  final  crop.  Those  removed  will  have  been  cut 
in  the  several  thinnings  when  the  trees  were  yet  immature,  in 
order  to  give  room  for  the  more  thrifty  trees.  The  revenue 
derived  from  such  thinnings  is  usually  figured  on  the  fuel  value  of 
the  wood.  Such  small  trees,  however,  if  cut  for  posts  or  even 
poles,  and  treated,  will  have  their  value  appreciably  augmented, 
so  that  thinnings  can  be  made  to  yield  a  larger  income.  Sup- 
pose the  plantation  is  loblolly  pine  and  the  first  thinning  is  made 
at  20  years,  600  trees  per  acre  being  removed.  These  will  be 
about  3  inches  in  diameter  and  20  feet  high,  hence  too  small  to 
be  used  advantageously  even  for  fuel.  The  first  thinning  will 
therefore  represent  a  direct  apparent  loss,  which,  however,  will 
be  recovered  by  the  accelerated  growth  of  the  remaining  trees. 
The  second  thinning  will  be  made  at  40  years,  and  400  trees  will 
be  removed.  These  will  have  reached  a  diameter  of  8  inches  and 
a  height  of  45  feet.  If  cut  for  fuel,  they  would  yield  about  13 
cords  worth  about  $1  per  cord  stumpage.  If  cut  into  posts,  how- 
ever, they  would  yield  about  1600  worth  at  2  cents  each  stump- 
age  a  total  of  $32.  Posts  of  this  species,  or  more  generally  of 
inferior  species,  are  worth  little  unless  treated,  but  when  treated 
their  durability  may  equal  or  excell  that  of  the  more  costly 
varieties,  so  that  it  will  often  prove  cheaper  to  use  them.  In- 
creased profit  derived  from  thinnings  will  enable  them  to  be  more 
systematically  and  carefully  made  and  thus  the  application  of  a 
more  intensive  system  of  forest  management  is  made  possible. 
The  practicability  of  a  forest  working  plan  depends  very  largely 
and  in  some  cases  entirely  upon  direct  financial  returns,  and  in 
any  case,  if  the  plan  can  be  made  to  produce  such  returns,  it 
will  enable  forest  principles  to  be  more  readily  applied. 

Other  things  being  equal,  conservative  lumbering  pivots  upon 


8  THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  value  of  the  top  logs.  Change  this  value  and  you  change  the 
system  of  marketing.  Wood  preservation  enables  the  top  and 
inferior  logs  to  be  used  to  better  advantage  than  if  left  in  the  woods 
to  rot  or  sawed  into  lumber.  By  raising  their  value,  it  intensi- 
fies the  utilization  of  timber  and  fosters  its  more  conservative  use. 
Thus  the  top  logs  of  such  trees  as  the  yellow  poplar,  black  walnut, 
maple,  birch,  etc.,  possess  so  little  value  that  they  are  often  left 
in  the  woods  to  rot,  or  when  sawed  into  lumber  are  frequently 
sold  at  a  loss.  For  example,  the  value  of  lumber  cut  from 
yellow  birch  logs  in  the  Adirondacks  in  1904,  14  inches  or  less  in 
diameter,  was  $9.37  per  thousand.  The  cost  of  stumpage,  log- 
ging, and  manufacturing  was  at  the  lowest  figure  $10.50  per  thou- 
sand. The  operators  therefore  lost  $1.13  per  thousand  on  all 
such  logs  removed.  For  beech  the  loss  amounted  to  $1.80  per 
thousand  feet  B.M.  If  these  logs  had  been  cut  into  railroad  ties, 
they  would,  at  $5  per  thousand  stumpage  and  15  cents  each  for 
logging  and  manufacture,  have  cost  about  32  cents  each  and  sold 
for  45  cents  each,  or  a  net  profit  of  about  $3.90  per  thousand  feet 
B.M.  Untreated  ties  of  this  species  have  little  use  on  account 
of  their  rapid  decay.  Some  lumber  companies  have  already 
realized  the  important  part  wood  preservation  is  playing  in  their 
operations  and  are  now  manufacturing  their  logs  which  are  in- 
ferior for  lumber  into  ties.  An  effective  system  of  forest  manage- 
ment will  recognize  this  and  will  change  the  manner  of  harvest- 
ing the  timber  so  as  to  get  greater  returns  from  it. 

Wood  preservation  accelerates  the  removal  of  fire-killed  and 
dead  timber  and  enables  areas  so  denuded  to  be  more  speedily 
reforested  and  placed  upon  a  profitable  basis.  Dead  timber, 
whether  standing  or  down,  decreases  in  value  each  year  and  land 
encumbered  with  it  can  be  likened  to  capital  stock  earning  no 
dividend  but  compelled  to  pay  annuities.  There  are  thousands 
of  acres  of  just  such  land  in  the  United  States.  It  is  often  im- 
practicable to  use  such  dead  trees  for  lumber  because  of  their 
extensive  checks,  the  stained  condition  of  the  wood,  or  holes 
bored  by  insects.  Furthermore,  on  account  of  rapid  decay,  the 
wood  may  not  be  usable  even  for  ties,  mine  props,  etc.  If 
treated  with  preservatives  much  of  this  timber  can  be  marketed. 
Tests  made  by  the  author  on  fire-killed  lodgepole  pine  in  Idaho 
proved  it  was  in  ideal  condition  for  preservative  treatment. 
When  cut  for  such  purposes  its  stumpage  value  in  comparison 
with  its  former  fuel  value  was  raised  about  60  percent. 


PLATE  I 


FIG.  A. — A  stand  of  young  Hodgepole  pine  in  Idaho.     (Forest  Service  photo.) 


FIG.  B. — Egyptian  coffin  dating  from  the  XII  dynasty  (2000-1788  B.  C.). 
The  only  restorations  are  three  cleats  on  the  bottom  of  the  coffin,  otherwise 
it  is  in  almost  perfect  preservation.  (Photo  through  courtesy  of  the  Metro- 
politan Museum  of  Art,  New  York.) 

(Facing  page  8.) 


PLATE  I 


FIG.  C. — Lentinus  lepidens.     (Forest  Service  photo.) 


FIG.  D. — Lenizites  sepiaria.     (Photo  through  courtesy  of  C.  J.  Humphrey.) 


INTRODUCTION  9 

History  of  Wood  Preservation.  Egypt— The  earliest  records 
of  the  artificial  preservation  of  organic  bodies  are  found  in  Egyp- 
tian history.  The  skill  show^n'by  the  Egyptians  in  enbalming 
bodies  proves  that  they  carried^he  art  to  a  high  state  of  perfec- 
tion. Apparently  the  "wooden  coffins  in  which  the  bodies  were 
placed  were  given  no  special  treatment,  so  that  their  durability 
can  be  accounted  for  only  by  the  exclusion  from  the  wood  of 
sufficient  moisture  to  allow  the  growth  of  wood-destroying 
organisms.  As  sycamore  was  largely  used  in  the  construction 
of  these  coffins,  this  furnishes  excellent  proof  of  the  durability 
of  wood  when  it  can  be  kept  dry;  in  fact,  in  such  a  condition  its 
life  is  indefinite.  (See  Plate  I,  Fig.  B.) 

Such  was  not  the  case,  however,  in  the  preservation  of  the  bod- 
ies. It  is  definitely  known  that  these  were  impregnated  with 
antiseptics,  although  the  exact  manner  in  which  this  was  done  is 
still  a  matter  of  conjecture.  From  the  writings  of  Herodotus 
it  appears  that  the  bodies  were  first  steeped  in  natrum  (a  natural 
substance  found  in  the  briny  lakes  near  Cairo  and  composed 
principally  of  sodium  sesqui-carbonate,  sodium  chloride,  and  so- 
dium sulphate)  for  about  2  months,  after  which  they  were  sub- 
jected to  a  bituminous  preparation,  perhaps  by  boiling  or  baking 
in  an  oven.  Pettigrew  extracted  the  preservatives  from  the  heart 
of  a  mummy  which  had  been  in  a  perfect  state  of  preservation 
for  over  3000  years,  and  the  heart  at  once  putrified.  Petti- 
grew's  experiments  show  that  the  mummies  prepared  in  natrum 
alone  were  not  as  well  preserved  as  those  in  which  solid  resins  or 
bitumens  were  found. 

Europe. — The  quantities  of  wood  used  by  the  early  Greeks 
and  Romans  in  their  buildings  and  bridges  caused  them  to  meet 
squarely  the  problems  of  preserving  it  from  decay.  Thus  among 
the  first  attempts  were  the  placing  of  stone  blocks  under  wooden 
pillars  to  keep  away  soil  and  vegetation.  The  tops  were  also 
capped  in  this  manner  and  it  is  thought  that  these  early  practices 
are  the  origin  of  the  base  and  capital  of  our  modern  stone  pillars. 
The  antiseptic  value  of  essential  oils  was  also  well  understood, 
these  being  obtained  from  the  olive  tree  and  from  various  cedars 
and  junipers  growing  along  the  Mediterranean.  The  practice 
was  to  either  rub  these  oils  over  the  surface  of  the  wood  to  be  pre- 
served, or  to  bore  numerous  small  holes  in  the  wood  and  pour  oil 
into  them.  In  this  manner  the  magnificent  statue  of  Jupiter  by 
Phideas  and  the  famous  statue  of  Diana  were  preserved.  Pliny 


10          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

asserts  that  the  oils  not  only  retarded  decay  but  kept  the  wood 
free  from  insect  attacks.  It  was  common  practice  among  the 
Romans  and  hut  dwellers  of  the  Baltic  to  char  their  timbers 
which  were  used  for  piling  before  placing  them  permanently  in 
their  structures.  This  method  of  preserving  wood  is  used  even 
to  the  present  day. 

It  was  perhaps  the  rapid  decay  of  timber  in  the  British  warships 
that  gave  wood  preservation  its  first  great  impetus.  It  is  re- 
ported that  40  acres  of  oak  forest  were  required  to  construct  a  70- 
gun  ship  and  that  the  great  prevalence  of  rot  in  the  vessels  as- 
sumed the  proportions  of  a  national  calamity.1  M.  Paulet  in  his 
book  entitled,  "  Conservation  des  Bois,"  enumerates  173  proc- 
esses or  methods  that  were  tried,  most  of  which  proved  unsuccess- 
ful. About  this  time  Holland  was  also  wrestling  with  the  pres- 
ervation of  the  timbers  used  in  the  construction  of  her  dykes  and 
marine  structures.  Later  came  the  development  of  the  steam 
engine  and  birth  of  the  locomotive,  which  brought  a  new  drain  on 
the  forest,  principally  for  cross-ties,  so  that  some  method  of 
preserving  wood  became  a  positive  necessity.  It  was  during 
the  first  quarter  of  the  19th  century  that  modern  methods  of 
injecting  wood  may  be  considered  as  beginning,  although  the 
most  successful  attempts  did  not  come  until  a  few  years  later. 
It  is  interesting  to  note  that  the  most  efficient  preservatives  were 
used  several  years  before  patents  were  taken  out  on  them,  or 
even  before  their  use  was  commercialized.  Thus  mercuric 
chloride  was  used  by  Homberg  in  1705  and  by  De  Boissieu  in 
1767,  although  it  is  with  Kyan's  name  that  the  salt  is  best  known, 
he  having  taken  a  patent  on  its  use  in  England  in  1832.  Even 
to  the  present,  its  use  is  commonly  called  "Kyanizing."  So  it  is 
with  copper  sulphate,  recommended  by  De  Boissieu  and  Borde- 
nave  in  1767  and  best  known  as  "Margaryizing,"  although 
Margary's  patent  was  not  granted  until  1837.  Chloride  of  zinc 
was  recommended  by  Thomas  Wade  in  1815  and  by  Boucherie 
in  1837  but  its  use  is  referred  to  as  " Bur netti zing"  from  the  pat- 
ents of  Sir  William  Burnett  in  1838.  Franz  Moll  took  out  a 
patent  in  1836  for  injecting  wood  in  closed  iron  vessels  with  oils 
of  coal-tar  but  the  practical  introduction  is  attributed  to  John 
Bethell,  whose  patent  is  dated  1838  and  whose  name  is  now  fam- 
ous in  the  art  of  preserving  timber.  It  is  reported  that  Bethell's 

1  The  Preservation  of  Timber  by  the  Use  of  Antiseptics."     Samuel  B. 
Boulton,  1885. 


INTRODUCTION  11 

process  required  the  timber  to  be  in  an  air-seasoned  condition 
before  the  preserving  oils  were  injected.  The  treatment  of  green 
timber  with  creosote  by  first^  using  steam  followed  by  a  vacuum 
prior  to  impregnation  with  the,jpil  is  attributed  to  Hayford.1 

The  marked  success1  met  with  by  the  use  of  the  preservatives 
mentioned  gave  a  pronounced  impetus  to  the  wood-preserving 
industry  throughout  Europe.  Later,  progress  was  directed  more 
to  perfecting  the  use  of  these  preservatives  than  in  attempting  to 
introduce  new  ones.  Thus  it  was  found  that  zinc  chloride  had  a 
tendency  to  leach  from  wood,  and  to  overcome  this  objection  as 
well  as  give  added  effectiveness  to  the  treatment,  Julius  Rutgers 
introduced  in  Germany  about  1874  a  method  of  treating  ties 
with  a  mixture  of  zinc  chloride  and  creosote.  This  method  has 
met  with  considerable  favor  in  Germany  and  is  now  one  of  the 
leading  processes  in  use  in  that  country.  The  excellent  results 
secured  with  coal-tar  creosote  have  always  caused  this  pre- 
servative to  be  held  in  very  high  repute.  Its  comparatively 
high  cost  led  Max  Reuping  to  take  out  a  patent  in  Germany  in 
1902  on  a  process  of  impregnating  it  into  wood,  and  subsequently 
withdrawing  a  part  of  it  so  that  the  total  amount  of  oil  actually 
consumed  was  greatly  reduced.  This  process  named  after  the 
inventor,  has  also  met  with  pronounced  success  in  European 
countries.  Several  other  methods  of  treating  wood  have  lately 
been  exploited  in  Europe  but  few  of  them  have  met  with  the  suc- 
cess of  the  Burnettizing  and  Bethell  processes. 

Wood  preservation  is  now  practised  in  all  the  leading  European 
countries.  In  England  creosoting  appears  most  popular,  while 
in  Germany  both  creosote  and  zinc  chloride  are  extensively  used. 
The  same  is  true  of  France,  where  appreciable  quantities  of  poles 
are  still  impregnated  with  copper  sulphate.  Not  only  ties  and 
poles  but  vast  quantities  of  mine  timbers,  paving  blocks,  piles, 
posts,  vineyard  sticks  and  lumber  are  now  annually  treated,  so 
that  the  industry  may  be  considered  as  permanently  established 
and  an  engineering  necessity.  Figures  on  the  amount  of  wood 
treated  in  Europe  are  not  available,  but  it  is  reported  that  about 
16,000,000  ties  are  annually  preserved  and  that  the  total  number 
of  plants  in  operation  is  about  70.  It  appears,  therefore,  that 
the  plants  in  Europe  have  on  the  average  a  much  smaller  capacity 
than  those  in  our  country. 

United  States. — The  commercial  application  of  wood  preserva- 

1  Reprint,  Journal  of  Franklin  Institute,  1878. 


12          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

tion  in  our  country  first  became  of  practical  importance  in  1848, 
when  a  Kyanizing  plant  was  built  at  Lowell,  Mass.  A  great 
many  tests,  however,  had  been  carried  on  in  a  more  or  less 
primitive  way  previous  to  this.  For  example,  Kyanized  chestnut 
ties  were  laid  near  Baltimore  in  1838  by  the  Northern  Central 
Railroad.  The  Lowell  plant  was  built  primarily  for  the  treat- 
ment of  timbers  used  in  the  locks  and  canals  on  the  Merrimac 
River.  It  operated  the  Kyanizing  process  for  2  years,  and  then 
substituted  the  zinc  chloride  method,  but  in  1862  the  officials, 
becoming  dissatisfied  with  these  treatments,  reverted  to  Kyaniz- 
ing, and  since  this  date  the  plant  has  been  in  more  or  less  con- 
tinuous operation. 

In  1856,  the  Vermont  Central  Railroad  erected  a  Burnettizing 
plant  for  the  treatment  of  bridge  timbers  and  ties,  but  it  was 
abandoned  after  being  in  operation  4  years.  About  this  time 
the  Chicago,  Rock  Island  and  Pacific,  the  Boston  and  Albany  and 
Erie  Railroads  built  plants  for  the  treatment  of  timber  with  zinc 
chloride.  All  these  plants  met  with  but  partial  success,  princi- 
pally because  of  the  then  abundant  supply  of  timber  and  the  high 
cost  and  inexperience  in  handling  treated  timbers.  Operators 
could  not  accustom  themselves  to  the  delay  which  timber  treat- 
ments entailed;  consequently  few  plants  treated  their  timber  for 
a  sufficient  period  to  enable  it  to  be  properly  impregnated  with 
the  preservative.  In  1863  the  Philadelphia,  Washington  and 
Baltimore  Railroad,  and  in  1867  the  Philadelphia  and  Reading 
Railroad  built  Burnettizing  timber-treating  plants,  but  both  had 
a  short  life  due  to  the  unsatisfactory  results  secured.  In  1865, 
the  Old  Colony  Railroad  erected  a  plant  at  Somerset,  Mass.,  for 
the  treatment  of  bridge  timbers  with  creosote.  This,  apparently, 
represents  the  first  practical  attempt  to  use  this  material  in  the 
United  States.  The  work  was  done  with  a  rush  and  in  a  careless 
manner,  much  of  the  timber  being  trimmed  after  it  was  treated. 
In  spite  of  this,  the  work  was  considered  a  success. 

In  1867,  Professor  Seeley  of  New  York  obtained  a  patent  for 
treating  timber  without  the  use  of  pressure.  He  erected  treat- 
ing plants  in  New  York,  Chicago,  and  at  the  St.  Clair  Flats  in 
Michigan.  His  claim  was  that  green  timber  could  be  treated 
just  as  effectively  as  seasoned  timber.  This,  however,  accounts 
in  a  large  measure  for  Seeley's  failure.  His  process  was  neverthe- 
less adopted  by  the  Government  for  its  work  at  the  St.  Clair  Flats 
in  the  construction  of  dikes,  etc.,  along  its  canal,  and  by  the 


INTRODUCTION  13 

Chicago,  Rock  Island  and  Pacific  and  the  Chicago,  Burlington 
and  Quincy  Railroads.  At  the  World's  Fair  in  St.  Louis  in  1904, 
von  Schrenk  revived  this  "open  tank"  process,  and  its  use  was 
later  on  made  the  subject  of  careful  study  by  the  U.  S.  Forest 
Service,  until  there  ar«  now  several  plants  in  operation  in  this 
country. 

About  the  time  Seeley's  process  was  being  promoted,  Mr.  L.  S. 
Robbins  introduced  a  method  in  which  he  impregnated  timbers 
with  vapors  of  creosote.  This  process  was  extensively  adver- 
tised and  local  companies  were  formed  in  New  York,  New  Jersey, 
Pennsylvania,  Massachusetts,  Connecticut,  and  California  with 
large  capital.  It  failed,  however,  in  practically  all  cases,  espe- 
cially where  it  was  used  in  marine  construction.  Mr.  C.  B.  Sears, 
engineer  in  charge  of  the  government  works  in  California,  states 
"that  it  failed  absolutely  to  protect  the  timber  from  the  Teredo, 
which  was  not  more  than  2  months  longer  in  attacking  it  than 
the  untreated  timber,  and  when  once  in,  its  action  seemed  to 
be  more  rapid." 

About  1870  Mr.  Thilmany  treated  a  great  many  ties  with 
copper  sulphate  and  barium  chloride  for  the  Wabash,  Pennsyl- 
vania and  Ohio,  Lake  Shore  and  Michigan  Southern,  Cleveland 
and  Pittsburg,  and  Baltimore  and  Ohio  railroads,  but  the  process 
met  with  the  fate  of  most  of  its  predecessors  and  it  was  eventually 
abandoned. 

In  1872,  it  is  reported,  Mr.  George  H.  Fletcher  boiled  some 
paving  blocks  in  dead  oil  of  coal-tar  and  laid  them  in  the  yard  of 
the  New  Orleans  Gas  Light  Company.  They  absorbed  about  20 
pounds  of  oil  per  cubic  foot  and  when  inspected  30  years  after- 
ward were  thoroughly  sound. 

Modern  timber  processes  may  be  considered  as  beginning  in 
this  country  in  1875,  when  a  creosote  plant  was  erected  at  West 
Pascagoula,  Miss.,  for  the  treatment  of  timbers  used  by  the  Louis- 
ville and  Nashville  Railroad.  This  plant  is  still  in  operation  and 
has  met  with  marked  success  in  its  work.  In  1878  Eppinger  and 
Russell  operated  their  creosote  plant  in  Long  Island  City,  N.  Y. 
In  1879  the  New  Orleans  and  North  Eastern  Railroad  built 
a  similar  plant  primarily  to  treat  the  timbers  used  in  the  bridge 
across  Lake  Ponchartrain.  From  this  period  on  the  wood- 
preserving  industry  has  permanently  grown,  the  Wyckoff  Pipe 
and  Creosoting  Company  erecting  a  plant  in  1881,  the  Colman 
Creosoting  Company  in  1884,  the  Santa  Fe  Railway  Company  in 


14          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

1885,  the  Chicago  Tie  Preserving  Company  in  1886,  etc.,  until 
at  the  present  time  there  are  now  about  90  plants  in  operation 
scattered  all  over  the  United  States  and  treating  annually  over 
125,000,000  cu.  ft.  of  wood.  (For  complete  list  see  Appendix.) 

It  is  interesting  to  note  that  the  first  successful  attempts  in 
timber  preservation  in  this  country  were  not  made  on  account  of 
scarcity  of  timber,  but  because  of  the  high  cost  of  replacing  it  after 
it  had  deteriorated.  For  example,  the  timber-treating  plant 
built  by  the  New  Orleans  and  North  Eastern  Railroad  was  erected 
to  treat  the  timbers  used  in  constructing  the  Lake  Ponchartrain 
bridge,  as  these,  without  treatment,  would  not  last  more  than 
3  or  4  years  due  to  rapid  decay  and  attack  by  borers. 
Although  treated  in  1875,  many  of  these  timbers  are  still  sound 
and  in  service.  Some  method  of  preserving  the  wood  was  there- 
fore an  absolute  necessity  to  the  railroad  company  in  order  to 
maintain  this  bridge.  Similar  conditions  prevailed  in  other 
places  along  the  Atlantic  Coast  and  in  mines,  but  the  gradual 
depletion  of  our  forests  and  rise  in  the  value  of  lumber  has  given 
a  further  impetus  to  the  growth  of  the  industry  so  that  there  are 
now  but  few  places  in  the  United  States  where  wood  preservation 
will  not  pay. 


.CHAPTER  II 

FACTORS    WHICH    CAUSE    THE    DETERIORATION    OF 
STRUCTURAL  TIMBER 

Discussion  of  Their  Relative  Importance. — Timber  placed  in 
service  is  subject  to  deterioration  from  many  causes,  and  its 
strength  eventually  becomes  so  weakened  that  it  must  be  re- 
moved and  replaced  with  sound  timber  or  some  other  material. 
The  chief  factors  which  cause  such  deterioration  are  decay, 
insects,  marine  borers,  mechanical  abrasion,  and  fire.  Others  of 
less  extent  are  alkaline  soils,  birds,  and  sand  storms.  Our 
country  is  so  vast  and  its  development  has  been  so  rapid,  that  it 
is  absolutely  impossible  at  this  time  to  even  estimate  with  any 
degree  of  accuracy  the  relative  importance  of  the  above  factors 
responsible  for  the  deterioration  of  structural  timbers.  In  the 
absence  of  statistics,  it  seems  very  probable,  however,  that  decay 
is  by  far  the  most  important,  as  enormous  quantities  of  wood  rot 
annually.  Next  in  rank  to  decay,  perhaps,  comes  mechanical 
destruction,  such  as  the  railcutting  of  ties;  then  in  gradually  de- 
creasing amounts,  fire,  insects,  and  marine  borers.  We  will  dis- 
cuss in  this  chapter  the  manner  in  which  these  destructive  agents 
work,  as  it  will  aid  in  understanding  the  protective  measures 
taken  to  overcome  them. 

Decay. — On  this  subject  volumes  have  been  written,  and  it 
seems  strange  that  even  at  the  present  time  the  cause  of  decay 
is  a  matter  little  understood  by  many  timber  treating  engineers.1 
For  this  reason  it  is  felt  desirable  to  review  the  more  essential 
facts  that  are  known  in  the  hope  that  they  may  clearly  fix  the 
basic  principles  of  fungous  growth.  The  prevailing  theory  about 
1840  as  to  the  cause  for  decay  in  timber  was  molded  by  the 
opinion  of  the  great  chemist  Liebig.  Liebig  taught  that  the  proc- 
ess of  fermentation  in  certain  fluids  and  the  putrefying  or  decay 
of  organized  bodies,  animal  and  vegetable,  were  caused  by  a 
species  of  slow  combustion  to  which  he  applied  the  term  "erema- 
causis;"  that  it  required  for  its  ordinary  development  the  pres- 

1  See  Proceedings  American  Wood  Preservers'  Association,  1912. 

15 


16         THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

ence  of  moisture  and  atmospheric  air;  that  its  action  was  pro- 
voked by  oxygen  and  its  method  of  action  was  by  a  communica- 
tion of  motion  by  the  atoms  of  the  affected  ferment  to  the  atoms 
of  the  body  affected.  He  denied  that  fermentation,  putrefaction, 
and  decomposition  were  caused  by  fungi,  parasites  or  infusoria, 
although  these  organisms  might  sometimes  be  present  during 
the  process.1 

With  the  introduction  of  the  microscope  and  the  consequent 
intensive  study  on  the  minute  forms  of  life,  the  theory  of  Liebig 
gradually  became  shattered.  The  bodies  of  mammoths  pre- 
served in  ice  through  countless  ages,  the  fragments  of  wooden 
piles  which  have  endured  undecayed  for  centuries  when  driven 
deeply  below  the  surface  of  water,  all  confirm  the  experiments  of 
Pasteur  and  Tyndall  and  prove  the  exclusion  of  germs  prevents 
decay.  Specimens  are  on  exhibition  of  a  sound  wooden  pile 
known  as  the  remains  of  a  bridge  (destroyed  by  fire)  which  was 
constructed  by  Charlemagne  across  the  Rhine;  of  pieces  of  piles 
in  the  foundation  of  the  bridge  across  the  Medway  at  Rochester, 
which  was  destroyed  by  Simon  de  Montfort  in  1264.  Thousands 
of  exact  laboratory  tests  have  established  beyond  all  peradven- 
ture,  that  the  true  cause  of  decay  in  timber  are  low  forms  of 
plants  called  fungi  and  bacteria.  The  action  of  bacteria  in  de- 
caying wood  is  not  clearly  known  even  to  this  day,  but  there  is 
little  reason  to  doubt  but  what  the  same  methods  used  in  com- 
bating fungi  will  prove  equally  as  effective  in  combating  them. 

Only  a  comparatively  small  percentage  of  fungi  and  bacteria 
have  the  ability  to  decay  wood  and  a  great  many  will  not  even 
grow  on  wood.  Of  those  which  do  grow  on  wood  it  is  customary 
to  divide  them,  in  a  discussion  of  this  kind,  into  " harmful"  or 
wood  destroying  and  " harmless"  or  saprophytic  fungi.  All 
fungi  are  forms  of  plants  which  are  parasitic,  that  is,  they  are 
dependent  on  other  plants  for  their  existence.  They  all  lack 
"chlorophyll,"  a  substance  which  gives  plants  their  green  color 
and  which  is  instrumental  in  taking  the  gases  from  the  air  and 
transforming  them  into  plant  substance. 

Fungi  reproduce  in  two  ways,  (1)  sexually,  by  means  of  minute 
"spores"  which  can  be  likened  to  tiny  seeds,  and  (2)  asexually, 
by  means  of  "mycelia"  which  can  be  likened  to  minute  roots. 
The  spores  are  blown  about  by  the  wind  like  very  fine  particles 

1  S.  B.  Boulton,  The  Preservation  of  Timber  by  the  Use  of  Antisep- 
tics, 1885. 


DETERIORATION  OF  STRUCTURAL  TIMBER  17 

of  dust,  and  when  they  -alight  on  wood,  start  to  germinate  and 
send  their  fine  mycelia  into  the  wood  gradually  decaying  it. 
If  these  mycelia  come  in  contact  with  sound  wood,  as  for  example, 
when  a  piece  of  decayed  wood  touches  a  piece  of  sound  wood,  they 
grow  into  the  sound  wood  and  ^11  ultimately  decay  it.  In  this 
way,  decay  is  also  spread.  Some  fungi  have  the  ability  to  send 
their  mycelia  over  materials  which  they  will  not  attack,  in  their 
search  for  wood.  Thus  if  two  pieces  are  separated  a  foot  or 
more  apart,  the  mycelia  from  the  decayed  piece  may  reach  out 
over  this  space  and  attack  the  sound  piece.  This  characteristic 
is  common  in  the  so-called  "  house  fungus/'  By  the  secretion 
of  little  understood  chemicals  by  these  mycelia,  the  wood  fiber 
is  dissolved  and  its  substance  serves  as  food  for  the  fungus. 
These  chemicals  are  termed  " enzymes"  or  " ferments."  Since 
fungi  vary  greatly  in  their  capacity  to  secrete  ferments,  we  have 
the  key  to  their  widely  varying  action  upon  timber.  It  is  only 
those  fungi  which  attack  cellulose  and  lignin  vigorously  that 
effect  the  durability  of  timber  to  any  serious  degree.  Give  them 
a  favorable  temperature  and  proper  moisture  and  air  supply  and 
the  destruction  proceeds  rapidly. 

Fungi  may  be  classified  in  regard  to  the  form  and  habit  of 
growth  of  the  " mushrooms"  technically  called  "fruiting  bodies." 
Based  on  these  characters,  the  "harmful"  or  wood  destroying 
fungi  may  be  divided  into  three  classes: 

1.  Fleshy  forms  of  the  "mushroom"  types  which  have  a  dis- 
tinct stem,  a  more  or  less  circular  cap  with  plates  or  "gills"  on 
the  under  side.     This  class  contains  few  destructive  forms.     (See 
Plate  I,  Fig.  C.) 

2.  Fungi  which  are  tough,  corky  or  woody  and  which  have  no 
stem,  but  are  attached  to  the  wood  by  the  side  of  their  rough 
semicircular  caps.  (See  Plate  I,  Fig.  D.)     The  under  surface  is 
provided   with  pores  of  various  outlines,  circular,  angular,  or 
sinuous.     Frequently  the  caps  grow  in  clusters,  one  above  the 
other.     This  class  contains  many  destructive  kinds. 

3.  Fungi  similar  to  those  in  class  (2),  but  whose  under  surface 
is  smooth  and  not  differentiated  with  pores  or  plates.     (See  plate 
II,  Fig.  a.) 

The   "harmless"   fungi   are  comparatively  few.     There  are 

several  species  similar  to  those  described  in  class  (1)  which  grow 

on  wood  after  it  has  reached  an  advanced  stage  of  decay.    Another 

form  (Schizophyllum  commune)  having  a  wide  distribution  is 

2 


18          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

small,  white,  thin,  leathery,  and  flexible,  and  has  a  bracket-like 
appearance.  It  frequently  occurs  on  sound  oak  or  pine  and  lives 
mostly  on  the  sugars  and  starches  in  the  wood.  Other  fungi 
which  are  white,  green,  brown  or  black  and  commonly  called 
"molds"  also  belong  to  the  " harmless"  group.  They  produce 
the  stain  in  wood  but  do  not  injure  its  strength  to  any  appreciable 
extent.1 

Insects. — The  deterioration  of  timber  through  insect  attack 
is  greatly  underestimated  in  this  country.  This  matter  has 
been  made  the  subject  of  a  special  investigation  by  the  U.  S. 
Bureau  of  Entomology  and  it  is  estimated  that  the  annual  loss 
from  this  cause  amounts  to  $100,000,000. 2  Round  timber  with 
the  bark  on,  such  as  poles,  posts,  mine  props,  saw  logs,  etc., 
is  particularly  subject  to  attack  by  round-headed  borers,  timber 
worms,  and  ambrosia  beetles.  Frequently  the  insects  continue 
the  work  in  the  unseasoned  and  even  dry  lumber  cut  from  logs 
which  had  been  previously  infested.  Their  prolonged  activities 
in  mine  timbers  is  well  known;  also  in  cabins,  and  rustic  furniture. 
Hickory  hoops  and  poles  are  often  rendered  worthless  by  borers 
and  beetles.  Stave  and  shingle  bolts,  handle  or  wagon  stock,  and 
pulpwood  are  peculiarly  subject  to  attack.  Although  termites 
are  not  usually  associated  with  the  destruction  of  timber  in  this 
country,  nevertheless  they  cause  considerable  damage  to  poles 
and  construction  timbers  used  in  buildings,  sometimes  completely 
destroying  them.  Many  of  the  insects  not  only  feed  on  the  wood 
but  burrow  into  it  for  their  protection  or  breeding  grounds.  This, 
of  course,  weakens  the  wood  and  allows  channels  through  which 
water  and  the  spores  of  destructive  fungi  can  enter.  Each 
specie  of  insect  has  its  own  peculiar  method  of  attack  so  that  it  is 
not  possible  in  a  treatise  of  this  kind  to  describe  all  of  them.  Two 
rather  typical  examples  will,  however,  be  given:  The  " powder- 
post  insect"  which  bores  into  dry  wood  and  the  "pole  borer" 
which  attacks  poles  and  similar  products. 

The  Powder-post  Insects.3— "The  adults  or  winged  forms  of  this  class 
of  insects  are  small,  slender  or  stout,  brownish  to  nearly  black  beetles, 

1  For  a  scientific  discussion  of  the  destruction  of  wood  by  fungi  and  bac- 
teria, the  reader  is  referred  to  Bulletin  266  of  the  U.  S.  Bureau  of  Plant  In- 
dustry, by  McBeth  and  Scales. 

2  Circular  129,  U.  S.  Bureau  of  Entomology,  A.  D.  Hopkins,  1910. 
8  Circular  55,  U.  S.  Division  of  Entomology,  by  A.  D.  Hopkins. 


PLATE  II 


FIG.  A. — A  red-oak  tie  attacked  by  a  wood  destroying  fungus  (stereum  fas- 
ciatum,  Schw.).     (Photo  through  courtesy  of  C.  J.  Humphrey.) 


I 


I 


FIG.  B. — (l)The  pole  borer,  male  and  female  beetles.     (2)  Young  larvae 
(Circular  134,  U.  S.  Bur.  Entomology.) 


(Facing  page  18  ) 


PLATE  II 


FIG.  C. — Gallery  of  the  pole  borer.       FIG.     D. — Mines   of   the   pole 

borer    near    the   surface   of   the 
ground. 

Work  of  the  pole  borer  (parandra  brumiea  Fab.)  in  an  untreated  chestnut 
pole.     (Circular  134,  U.  S.  Bur.  of  Entomology.) 


DETERIORATION  OF  STRUCTURAL  TIMBER  19 

which  upon  emerging  from  the  wood  where  they  breed  and  pass  the  win- 
ter, fly  or  crawl  about  in  search  of  suitable  wood  material  in  which  to 
deposit  their  eggs. 

The  different  species  vary  in  their  habits  and  life  history,  from  the  egg 
to  the  adult,  but  in  general  that  ofcthe  true  powder-post  beetles  is  as 
follows :  The  winter  is  passed  in  the  wood.  The  eggs  are  deposited  under 
normal  conditions  soon  after  activity  commences  in  the  spring,  while 
in  storehouses  and  buildings  kept  warm  and  dry  they  may  continue  their 
activity  through  the  year  and  deposit  eggs  much  earlier.  The  minute 
wrhite  "worm"  or  grub  (the  second  stage  of  the  insect  known  as  the 
larva),  upon  hatching  from  the  egg,  proceeds  to  burrow  in  and  through 
the  wood  in  all  directions,  feeding  and  growing  as  it  proceeds,  until  it  has 
attained  its  full  growth.  It  then  excavates  a  cell  at  the  end  of  its  burrow, 
in  which  it  transforms  to  a  semidormant  stage  (the  pupa,  or  third  stage 
in  the  insect's  life),  remaining  thus  until  the  legs  and  wings  have  fully 
developed,  when  it  bores  its  way  out  and  appears  as  the  matured  adult  or 
beetle  (the  fourth  stage),  to  mate  and  repeat  the  life  process.  Under 
normal  conditions,  so  far  as  is  positively  known,  there  is  probably  only 
one  generation  annually. 

Each  female  deposits  many  eggs,  and  many  females  oviposit  on  or  in  a 
single  piece  of  wood,  so  that  the  combined  work  of  their  numerous  pro- 
geny, borrowing  through  the  wood  in  quest  of  food  for  their  development, 
results  in  the  complete  destruction  of  the  interior  wood  fiber  and  its  con- 
version into  a  mass  of  fine  powder.  If  the  first  attack  and  the  first 
generation  do  not  accomplish  this  destruction,  subsequent  generations 
will  follow  in  the  same  wood  until  nothing  of  the  solid  fiber  is  left  but  a 
thin  outer  shell." 

The  Pole  Borer.1 — This  insect  (Parandra  brunnea  Fab.),  is  an 
elongated,  creamy-white,  wrinkled,  round-headed  grub  or  larva. 
(See  Plate  II,  Fig.  B-2.)  It  hatches  from  an  egg  deposited  by  an 
elongate,  mahogany-brown,  shiny,  flattened,  winged  beetle,  from 
two-fifths  to  four-fifths  of  an  inch  in  length.  (See  Plate  II,  Fig.  B-l .) 
It  appears  that  the  eggs  are  deposited  from  August  to  October  in  the 
outer  layers  of  the  wood  of  the  pole  near  the  surf  ace  of  the  ground. 
The  young  borers,  upon  hatching,  excavate  shallow  galleries  in 
the  sap  wood,  then  enter  the  heartwood,  the  mines  being  gradually 
enlarged  as  they  develop.  As  they  proceed  they  closely  pack 
the  fine  boring  dust  behind  them.  This  peculiar  semidigested 
boring  dust,  which  is  characteristic  of  their  work,  is  reddish  to 
dunnish  yellow  in  color  and  has  a  clay-like  consistency.  The 
burrows  eventually  end  in  a  broad  chamber,  the  entrance  to  which 

1  Circular  134,  U.  S.  Bureau  of  Entomology,  by  T.  E.  Snyder. 


20          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

is  plugged  with  excelsior-like  fibers  of  wood.  Here  is  formed  the 
resting  stage,  or  pupa,  which  transforms  to  the  adult  beetle. 
Often  all  stages,  from  very  young  grubs  only  about  one-fourth 
inch  long  to  full-grown  grubs  over  1  inch  long,  pupae,  and  adults 
in  all  stages  to  maturity  are  present  in  the  same  pole.  Adults 
have  been  found  flying  from  July  to  September. 

The  insect  attacks  poles  that  are  perfectly  sound,  but  will  work 
where  the  wood  is  decayed ;  it  will  not,  however,  work  in  wood  that 
is  "sobby"  (wet  rot),  or  in  very  "doty"  (punky)  wood.  It 
has  not  yet  been  determined  just  how  soon  the  borers  enter  the 
poles  after  they  have  been  set  in  the  ground.  However,  poles 
that  had  been  standing  only  4  or  5  years  contained  larvaa  and 
adults  of  this  borer  in  the  heartwood,  and  poles  that  had  been 
set  in  the  ground  for  only  2  years  contained  young  larvae  in 
the  outer  layers  of  the  wood. 

The  presence  of  the  borers  in  injurious  numbers  can  be  de- 
termined only  by  removing  the  earth  from  about  the  base  of  the 
pole;  the  large  holes  made  when  the  adults  come  out  are  found 
near  the  line  of  contact  with  the  soil.  Often  large,  coarse  borings 
of  wood  fiber  project  from  these  exit  holes.  Sometimes  the  old 
dead  parent  adults  are  found  on  the  exterior  of  the  poles  under- 
ground. During  August  the  young  adults  may  be  found  in 
shallow  depressions  on  the  exterior  of  poles  below  the  ground 
surface. 

Marine  Borers. — In  many  places  along  both  the  Atlantic  and 
Pacific  coasts  timber  used  for  piles  in  wharfs  and  other  marine 
structures  is  attacked  by  marine  wood  borers.  There  are  many 
kinds  of  such  borers  but  those  which  occur  in  our  waters  can  be 
classed  into  three  genera  of  mollusks,  Xylotrya,  Nausitoria,  and 
Teredo,  commonly  known  as  "ship worms,"  and  three  of  crus- 
taceans, Limnoria,  Chelura,  and  Sphseroma,  commonly  called 
"wood  lice." 

The  activities  of  the  shipworms  were  known  to  the  ancient 
Romans,  who  sheathed  their  ships  against  them.  Clement 
Adams  in  the  reign  of  Henry  VI  notes  that  upon  the  squadron 
sent  out  to  discover  the  Northeast  Passage — "they  cover  a  piece 
of  the  keels  of  the  shippe  with  their  sheets  of  leade,  for  they  had 
heard  that  in  certaine  partes  of  the  ocean  a  kinde  of  wormes  is 
bredde,  which  many  times  pearceth  and  eateth  through  the 
strongest  oake  that  is."1 

1  "Voyages  and  Travels"  Vol.  II,  C.  R.  Beazley. 


DETERIORATION  OF  STRUCTURAL  TIMBER  21 

Xylotrya,  Nausitoria,  and  Teredo1  in  structure  and  mode  of 
life  are  very  much  alike.  Hence  for  all  practical  purposes  a 
description  of  the  work  of  Xylotrya  will  be  sufficient  (see  Fig. 
1).  The  average  diameter  of  an  egg  is  less  than  1/500  inch,  and 
a  single  worm  may  lay^  100  mimon  in  a  season.  When  the  egg 
hatches,  the  embryo  swims  around  for  about  a  month  and  the 
exposed  surface  of  the  wood  is  then  attacked  by  countless  thou- 
sands of  them  which  immediately  begin  to  bore.  The  hole  by 
which  it  enters  is  minute,  but  beneath  the  surface  the  burrow  is 
soon  enlarged  to  accommodate  the  rapidly  growing  body.  The 
burrow  extends  usually  in  a  longitudinal  direction  and  follows 
a  very  irregular,  tangled  course. 

There  is  some  controversy  as  to  the  method  by  which  boring 
is  accomplished.  It  is  possible  that  the  body  is  held  rigidly  by 


FIG.  1. — Xylotrya  or  ship  worm. 

an  extensile  sucker-like  foot,  ordinarily  incased  within  the  two 
shell  valves  (Fig.  1,  a),  and  that  the  two  valves  revolve  around 
this,  cutting  the  wood  away  with  fine,  hard,  tooth-like  protuber- 
ances. It  is  possible  on  the  other  hand  that  the  muscular  ring 
near  the  posterior  end  of  the  body  (Fig.  1,  6)  is  pressed  firmly 
against  the  walls  of  the  burrow;  and  that  the  whole  body,  including 
the  shell  valves  and  foot,  revolves  slightly  in  both  directions,  the 
shell  valves  doing  the  cutting.  It  is  probable,  however,  that  the 
boring  is  done  by  a  united  action  of  the  valves  and  foot.  The 
posterior  muscular  end  is  probably  the  only  portion  of  the  body 
held  rigid.  The  valves  revolve  slightly,  cutting  into  the  wood, 
partially  in  front  and  partially  on  the  sides.  At  the  same  time 

1  Circular  128,  U.  S.  Forest  Service,  "  Preservation  of  Piling  against  Mar- 
ine Borers,"  by  C.  S.  Smith,  1908. 


22          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  foot,  either  by  the  secretion  of  an  acid  substance,  or  of 
spicules  used  as  a  grinding  medium,  assists  in  breaking  down  the 
wood  fibers  directly  in  front  of  the  advancing  mollusk.  The 
hardest  knots  are  penetrated  with  ease,  but  the  softer  parts  of  the 
wood  are  preferred.  As  the  body  grows  it  secretes  a  calcareous 
substance  to  form  a  hard  lining  around  the  burrow.  This  is 
thicker  in  soft,  porous  woods  than  in  those  which  are  hard  and 
dense. 

At  the  posterior  end  of  the  body,  just  below  the  muscular  ring, 
are  two  siphons,  or  tubes  (Fig.  1,  c).  Through  the  shorter  one 
the  fine  borings  are  ejected  with  the  excreta;  through  the  longer 
one  water  and  food  are  taken  in.  The  food  consists  wholly  of 
infusoria,  and  is  not  obtained  from  the  wood  itself.  The  sole 
object  of  boring  into  the  wood  is  to  secure  a  place  of  shelter. 

Xylotrya  rapidly  attains  maturity.  High  temperatures  pro- 
mote quick  work  and  hasten  bodily  development.  The  size 
attained  by  the  adult  depends  upon  the  species,  the  locality,  and 
the  obstacles  to  excavation.  In  rare  cases  a  length  of  6  feet,  with 
a  diameter  of  over  1  inch,  is  said  to  be  attained.  Other  species 
seldom  attain  a  length  of  over  5  inches  or  a  diameter  of  over 
1/4  inch. 

The  portion  of  the  pile  commonly  attacked  is  that  between 
mean  tide- water  mark  and  a  point  about  4  feet  below  low  water, 
though  sometimes  it  extends  downward  as  far  as  the  pressure 
of  the  water  will  permit.  The  entrance  holes  do  not  indicate  the 
extent  of  attack,  as  the  entrance  may  be  at  mean  tide-water 
mark  and  the  active  boring  head  several  feet  above.  On  the 
other  hand,  part  of  the  excavation  may  be  below  the  mud  line, 
though  the  entrance  is  never  so  situated.  More  than  half  of  the 
weight  of  the  structure  may  be  removed  without  any  visible  signs 
of  deterioration  upon  the  surface.  When  the  worm  is  dead,  the 
minute  entrance  holes  often  become  filled  with  mud  or  debris, 
so  that  it  is  impossible  to  discover  the  true  condition  of  the  pile 
without  chopping  into  it. 

The  Phola  is  primarily  a  marine  stone  borer  but  certain  species 
will  attack  wood.  In  form  it  resembles  a  long  clam.  In  boring 
it  braces  its  open  shell  against  the  sides  of  its  excavation,  while  its 
long  sucking  foot  emerges  and  rubs  the  surface  of  the  stone  or 
wood.  Particles  of  sand  are  operated  between  the  foot  and  the 
stone  or  wood,  thus  grinding  the  excavation.  Granite,  marble, 
or  any  kind  of  stone  seems  to  be  attacked.  Fortunately,  its 


DETERIORATION  OF  STRUCTURAL  TIMBER  23 

ravages  on  wood  are  not  as  extensive  as  the  Xylotrya  and 
Teredo. 

Undoubtedly  all  shipworms -thrive  best  under  the  influence  of 
heat,  though  some  can  endure  a  relatively  low  temperature. 
Certain  species  have  been  reported  from  as  far  north  as  Eastport, 
Me.  Since  warm  water  increases  their  activity  and  permits 
them  to  continue  their  attacks  throughout  the  greater  portion 
of  the  year,  shipworms  are  most  destructive  from  Chesapeake 
Bay  south  to  Florida,  on  the  Gulf  of  Mexico,  and  along  the  entire 
Pacific  coast. 

The  shipworm  may  be  present  in  some  waters,  yet  absent  in 
others  near  by.  This  is  usually  due  to  a  difference  in  the  water. 
Xylotrya  appears  to  be  able  to  endure  the  brackish  water  of  the 
inner  New  York  Harbor,  while  Teredo  cannot  live  there,  though 
it  is  present  in  the  ocean  just  outside.  The  shipworm  is  very 
active  on  the  north  Pacific  Coast,  yet  it  is  absent  about  the  mouth 
of  the  Columbia  River,  where  the  amount  of  salt  in  the  ocean  is 
influenced  by  the  inflow  of  fresh  water.  The  effect  of  water 
conditions  was  also  noticed  in  Holland  during  certain  years  in 
which  the  worms  were  unusually  destructive.  Little  rain  fell 
during  those  years,  and  the  small  amount  of  river  water  brought 
to  the  coast  was  thought  to  have  allowed  the  ocean  to  become 
more  saline  about  the  mouths  of  these  streams.  Analyses  show 
that  there  is  a  variation  in  the  proportion  of  salt  present  in  the 
waters  of  the  coast  during  the  dry  and  the  rainy  seasons. 

Observations  along  Chesapeake  Bay  and  the  Gulf  of  Mexico 
indicate  the  species  found  there  will  thrive  in  waters  with  a  saline 
density  indicated  by  a  specific  gravity  of  from  1.0054  to  absolute 
saturation,  1.0333;  that  they  thrive  in  temperatures  of  from 
55°  F.  to  the  highest  found  along  our  coasts;  that  they  work  in 
absolutely  clear  and  in  very  turbid  water;  that  they  seldom  work 
to  a  depth  of  over  30  feet;  and  that  the  worst  attack  is  usually  in 
the  very  salty,  warm,  clear  waters. 

The  length  of  time  required  to  destroy  an  average,  barked  un- 
protected pine  pile  in  different  localities  is  shown  in  the  following 
table: 

From  this  table  it  will  be  seen  that  the  average  life  of  an  un- 
treated pine  pile  on  the  Atlantic  coast  south  from  Chesapeake 
Bay  and  along  the  entire  Pacific  coast  is  but  from  1  to  3 
years. 


24 


THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


Length  of  life 

reported 

Average              | 

Minimum 

Colon,  Panama     

9  months-1  year 

Norfolk,  Va 

5  years 

1  year 

Newport  News,  Va  

2  years  

Hampton  Roads             

1  1/2  years  

St  Andrews   Fla 

2-3  years 

Pensacola,  Fla  
Fort  Morgan,  Ala. 

2-3  years  

1  year 
1  year 

West  Pascagoula,  Miss  

2-3  years  

1  year 

Texas  City,  Tex  
Galveston,  Tex 

1  year  
11/2  years 

29  days 
5  months 

Aransas    Pass,    Tex  
Puget  Sound 

1  year  
1  year 

3  months 

Klawak,  Alaska  

3  years  

18-20  months 

Of  the  crustacean  borers,  Limnoria,  or  the  "wood  louse,"  is 
the  only  one  of  great  importance  (Fig.  2).  It  is  gregarious  in  its 
habits,  and  is  about  the  size  of  a  grain  of  rice.  The  wood  in 
which  it  tunnels  furnishes  both  food  and  shel- 
ter. Boring  is  done  with  very  sharp  man- 
dibles. The  little  galleries  excavated  are  about 
1/2  inch  long  and  only  slightly  larger  in  dia- 
meter than  the  borer.  The  galleries  extend 
inward  radially,  side  by  side,  in  countless 
numbers,  so  that  the  wood  partitions  between 
them  are  very  thin  and  are  soon  destroyed  by 
wave  action,  thus  exposing  a  fresh  wood  sur- 
face to  attack.  Boring  is  carried  on  at  the 
rate  of  about  1/2  inch  per  year.  Soft  and 
hard  woods  are  both  destroyed,  but  soft  woods 
much  more  quickly.  If  possible,  knots,  dense 
summerwood,  and  other  obstructions  are 
avoided.  The  attack  is  usually  centered  upon 
a  limited  zone  above  and  below  low-water 
mark.  Hence  where  the  tide  is  great  the 
surface  exposed  to  attack  is  large. 

Limnoria  is  reported  by  the  U.  S.  Fish  Commission  as  occurring 
rarely  at  a  depth  of  40  feet.  It  has  a  wider  temperature  range 
than  Xylotrya,  but  requires  pure  salt  water  and  cannot  exist 
in  dirty  or  fresh  water.  It  is  found  along  the  Atlantic 
coast  from  Florida  to  Nova  Scotia.  It  occurs  sparingly  in  Long 
Island  Sound,  is  quite  abundant  along  the  coast  of  Massachusetts 


FIG.  2. — Limnoria. 


DETERIORATION  OF  STRUCTURAL  TIMBER  25 

and  in  the  Bay  of  Fundy.  It  also  does  great  damage  along  the 
whole  Gulf  of  Mexico,  on  the  north  Pacific  coast  around  Puget 
Sound,  and  in  the  Straits  of  pa^n  Juan  de  Fuca. 

All  the  woods  commonly  use<jj,for  piling  are  subject  to  the  at- 
tacks of  marine  borers.*  Some  doubt  has  been  expressed  whether 
borers  attack  certain  species  which  are  not  indigenous  to  this 
country  and  some  native  woods  that  have  an  extremely  porous 
structure.  Examples  of  the  first  class  are  certain  eucalypts,  and 
of  the  second  class,  palms  and  palmettos.  From  investigation  it 
is  clear  that  species  of  the  first  class  are  not  immune  from  attack, 
and  that  those  of  the  second,  although  practically  immune,  are 
found  in  such  small  quantities  and  are  so  lacking  in  the  require- 
ments of  structural  timbers  that  the  fact  is  not  important.  Hard- 
ness is  no  barrier  to  attack,  although  boring  is  probably  slow  in 
dense  woods  like  ebony,  eucalyptus,  etc.  Whenever  partial  or 
complete  immunity  is  reported,  it  is  perhaps  largely  due  to  local 
conditions  rather  than  to  the  kind  of  wood. 

Mechanical  Abrasion. — Wood  placed  in  service  is  often  de- 
stroyed solely  from  mechanical  causes,  and  when  these  cannot  be 
mitigated  or  eliminated,  the  protection  of  such  wood  from  decay 
is  frequently  inadvisable.  Of  the  various  forms  of  structural 
timbers,  cross- ties  are  most  subject  to  serious  mechanical  wear, 
and  the  loss  from  this  cause  is  estimated  at  15  percent  of  the  total 
number  of  ties  annually  destroyed.  Wood  paving  blocks,  piling, 
and  planking  used  in  piers,  timbers  in  cars,  and  all  forms  of 
vehicles,  mine  props,  etc.,  are  subject  to  mechanical  deterioration. 
In  many  cases  no  protection  can  be  afforded  the  timber  from  such 
loss,  as,  for  example,  occurs  in  mine  props  subject  to  " squeeze." 
It  frequently  happens,  however,  that  the  wood  can  be  protected 
by  coating  its  surface  with  some  hard  substance  such  as  iron  on 
those  portions  where  the  abrasion  occurs.  At  times,  protection  is 
afforded  by  coating  the  permanent  timbers  with  timbers  that  are 
only  temporary  and  whose  function  it  is  to  absorb  shock  and  stand 
all  wear. 

Fire. — The  action  of  intense  heat  on  wood  is  so  well  understood 
that  little  or  no  comment  is  necessary.  Combustion,  of  course, 
occurs,  the  wood  being  decomposed  into  carbon  dioxide,  water 
vapor,  and  ash,  so  that  its  original  properties  are  completely 
changed.  Wood  which  is  wet  or  is  in  a  green  condition  is  much 
more  difficult  to  ignite  than  wood  which  is  dry,  because  it  can 
absorb  considerably  more  heat  units  in  converting  the  water  it 


26          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

contains  into  steam.  Consequently,  wood  containing  high 
percentages  of  water  is  less  liable  to  injury  from  fire  than  wood 
which  is  dry.  Most  structural  timbers,  however,  particularly 
those  used  in  buildings  where  they  are  protected  from  the 
weather,  are  sufficiently  dry  so  that  they  can  easily  be  ignited. 
The  fire  losses  in  the  .United  States  are  enormous,  reaching  a  sum 
estimated  at  $215,000,000  a  year.  Of  course,  the  value  of  the 
timber  actually  destroyed  is  but  a  small  percentage  of  this 
amount,  most  of  it  being  for  labor  of  construction  and  for  other 
materials  and  products.  There  is  no  doubt  but  what  this  loss  can 
be  very  materially  reduced,  as  is  shown  by  conditions  abroad,  but 
to  secure  most  successful  results  it  is  felt  that  the  building  itself 
should  not  only  be  fire-retardant  but  that  as  many  of  its  contents 
as  possible  should  also  be  made  to  resist  the  flames,  and  the  general 
public  educated  to  exercise  caution. 

Minor  Factors. — In  addition  to  the  factors  just  discussed,  there 
are  a  number  of  others  of  minor  importance  which  destroy  or 
injure  wood.  The  chief  of  these  are  alkaline  soils,  birds,  sapstain 
and  sand  storms. 

Alkaline  Soils. — In  many  portions  of  the  United  States,  par- 
ticularly in  the  West,  vast  areas  of  soil  are  more  or  less  alkaline. 
Generally  speaking,  two  kinds  of  alkaline  soils  are  recognized, 
" black"  and  " white"  alkali.  Black  alkali  is  sodium  carbonate 
while  the  white  is  sodium  sulphate  and  other  sodium  salts.  It 
has  been  repeatedly  claimed  that  wood  in  contact  with  such  soil 
will  be  rapidly  attacked  and  soon  become  worthless.  Pieces  of 
wood  flumes,  poles,  and  ties  have  been  received  that  were  claimed 
to  have  been  destroyed  by  the  soil.  In  all  cases  examined  the 
specimens  showed  the  presence  of  wood-destroying  fungi.  For 
example:  Mr.  A.  0.  Campbell,  Assistant  Engineer  of  the  Oregon 
Short  Line  Railroad  Company,  submitted  for  analysis  in  1908 
several  samples  of  ties,  ballast,  and  soil  which  he  took  from  a 
portion  of  the  line  known  as  the  Lucin  Cutt-off  between  Ogden 
and  Lucin,  Utah.  These  ties  had  completely  deteriorated  in 
about  8  years.  A  chemical  analysis  showed  the  water- 
soluble  materials  washed  from  the  ballast  and  soil  in  which  the 
ties  were  placed  contained  about  6  percent  of  sodium  carbon- 
ate. A  microscopic  examination  of  the  wood,  however,  showed 
it  to  be  full  of  fungus  mycelia.  It  is  thought  that  the  amount 
of  alkali  in  most  alkaline  soils  is  too  small  to  seriously  affect  the 
strength  of  wood  in  contact  with  it,  but  that  under  certain  condi- 


PLATE  III 


FIG.  A. — Cedar  ties  badly  damaged  by  rail  cutting.  Upper  section 
shows  tie  without  plate,  lower  section  shows  tie  plate  was  too  small.  (Forest 
Service  photo.) 

(Facing  page  26.) 


PLATE  III 


FIG.  B. — Poles  destroyed  by  a  sleet  storm  in  Maryland,  1904.     (Forest 

Service  photo.) 


FIG.  C. — Results  of  a  fire  at  the  Arlington  Manufacturing  Company's 
Mill,  Arlington,  N.  J.  In  rebuilding,  wood  beams  were  used  throughout. 
(Photo  courtesy  of  the  Boston  Mfg.  Mutual  Fire  Ins.  Co.) 


DETERIORATION  OF  STRUCTURAL  TIMBER  27 

tions  of  warm  temperature  and  abundant  moisture,  chemical 
action  between  the  alkali  and  the  wood  might  occur  and  deteriora- 
tion result  in  time.  As  the  t  chemical  action  of  these  alkalies 
upon  wood  even  under  the  most  favorable  conditions  is  but  slight, 
as  is  indicated  by  tests  to  reduce  wood  to  pulp,  most  of  the  trouble 
that  has  been  experienced  can  be  attributed  to  decay. 

Birds. — Woodpeckers  are  the  only  birds  which  are  charged 
with  the  destruction  of  structural  timber.  Telephone  and 
telegraph  poles  seem  to  be  the  chief  forms  attacked,  although 
at  times  they  will  drill  holes  into  dwellings.  In  1906,  the 
author  made  a  count  in  Louisiana  of  a  number  of  telegraph  poles 
attacked  by  woodpeckers.1  Out  of  268  poles,  110  or  41  percent 
had  been  bored  into.  In  southern  Indiana  another  examination 
was  made  of  two  pole  lines  near  Greenwood.  In  one,  which 
extended  north,  21  percent  of  89  poles  examined  had  been 
attacked,  and  in  the  other,  which  ran  south,  out  of  58  poles  only 
59  percent  were  uninjured. 

The  woodpeckers  which  are  most  injurious  are  the  ant-eating 
woodpecker  (Melauerpes  formicivorous) ,  the  gold-fronted  wood- 
pecker (Centurus  aurifrous),  and  the  red-headed  woodpecker 
(Melauerpes  authrocephalus) ,  this  latter  species  being  the  one 
common  in  our  northern  states.  The  poles  are  attacked  by  the 
birds  chiefly  for  the  insects  contained  in  them  or  for  nesting  sites. 
In  some  cases,  however,  particularly  with  the  ant-eating  wood- 
pecker, they  are  used  as  a  storehouse  for  food.  These  birds  will 
frequently  fly  for  miles  with  an  acorn  in  their  bill,  drill  a  hole  in  a 
pole,  and  insert  the  acorn  in  it,  to  be  used  later  for  food. 

Woodpeckers  usually  attack  a  pole  near  its  top,  although  at 
times  they  may  bore  within  a  few  feet  of  the  ground.  Some 
observations  made  on  a  telegraph  line  paralleling  a  railroad  in 
Tennessee  showed  that  those  poles  which  were  imbedded  in  hill 
tops  above  the  level  of  the  track  were  the  ones  most  seriously 
attacked,  while  those  which  were  in  the  valleys  so  that  their 
tops  were  not  higher  than  the  level  of  the  track  were  seldom  at- 
tacked. The  number  of  holes  in  a  pole  may  vary  from  one  to  a 
dozen  or  more,  although  these  larger  numbers  are  not  common. 
The  size  of  the  hole  varies  from  about  1/2  inch  to  3 
inches  in  diameter.  When  used  for  nesting  sites,  the  birds  may 

1  Some  observations  on  the  attack  of  poles  by  woodpeckers. — H.  F.  Weiss, 
Engineering  News,  January,  1911. 


28 


THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


hollow  out  a  pocket  6  or  10  inches  in  diameter  and  a  foot  or  more 
in  depth. 

The  question  of  interest  to  telephone  engineers  is  to  just  what 
extent  such  poles  are  weakened.  It  has  been  found  from  measure- 
ments that  a  30-foot  northern  white  cedar  pole  tapers  approxi- 
mately as  follows: 


Circumference  (inches) 

43 

37 

36 

34 

32 

29 

27 

24.. 


Distance  from  butt  (feet) 

0 

.   5 


10 
15 
.20 
25 
30 


Assuming  the  pole  a  cantilever  beam  loaded  at  one  end,  it  is 
found  that  it  may  be  hollowed  to  the  extent  shown  in  Fig.  3 

without  decreasing  its  strength.  For 
example,  at  10  feet  from  the  ground  if 
only  2  inches  of  the  outer  shell  are 
left,  the  pole  will  be  approximately  as 
strong  as  though  it  were  solid.  If, 
however,  the  attack  is  less  than  4  feet 
from  the  ground,  the  pole  will  be 
weakened.  This  illustration  neglects 
the  damage  done  by  the  entrance  into 
the  pole  or  the  subsequent  decay  which 
may  follow,  and  assumes  that  the  bird 
builds  its  nest  exactly  in  the  center. 
On  the  other  hand,  it  assumes  that 
the  pole  has  a  uniform  moisture  con- 
tent throughout  its  length  and  that 
the  outer  fibers  of  wood  at  the  ground 
line  are  sound. 

FIG.  3.— Diagram  show-       The  American  Telephone  and  Tele- 
ing  the  extent  to  which  a  graph  Company  made  a  few  tests  in 
"OS  near  Zanesville,   Ohio,  to   deter- 
mine  the  effect  of  woodpecker  attacks 
on  the  strength  of  poles.     These  tests  were  made  by  fastening 
a  rope  -around  the  top  of  the  pole  and  pulling  with  a  block  and 
tackle  to  which  a  dynamometer  was  attached.     In  nine  out  of 


012345 

Eadius  of  Pole,  Inches 


DETERIORATION  OF  STRUCTURAL  TIMBER 


29 


twelve  cases  the  poles  broke  at  the  ground  line  and  not  at  the 
points  attacked  by  the  birds.  It  appears,  therefore,  that  the 
destruction  of  poles  by  birds  is>  but  very  slight  and,  considering 
the  good  which  they  do  in  ^destroying  insects,  is  no  justifica- 
tion for  killing  them.  *> 

Sap  Stain. — When  freshly  cut  sap  lumber  is  piled  in  the  open  air 
to  season  it  frequently  becomes  discolored  in  a  few  days.  This 
discoloration  is  not  due  to  weathering  but  to  the  growth  of  certain 
fungi  which  live  upon  the  materials  in  the  sapwood  cells.  Wood 
thus  attacked  is  considered  defective  and  its  value  is  frequently 
reduced  from  50  cents  to  $2  per  1000  feet  board  measure.  Perhaps 
one-fourth  of  the  annual  mill  cut  of  the  United  States  is  attacked, 
the  most  severe  damage  being  in  the  South.  Any  locality  where 
warm  damp  air  surrounds  the  lumber  is  favorable  to  the  produc- 
tion of  stain.  Estimates  for  the  whole  country  place  the  annual 
loss  from  sap  stain  at  about  eight  million  dollars. 

It  is  commonly  held  that  lumber  attacked  by  stain  is  decayed 
and  hence  reduced  in  strength.  This  decay  apparently  is  very 
slight,  because  the  fungi  which  produce  the  stain  do  not  attack 
the  wood  substance  to  any  appreciable  extent  but  rather  live 
upon  the  materials  stored  in  the  cells  of  the  wood.  Carefully 
conducted  tests  on  stained  and  unstained  wood  were  made  by 
the  Forest  Products  Laboratory  at  Madison,  Wis.,  the  results 
of  which  are  shown  in  Table  2. 

TABLE  2. — SUMMARY  OF  TESTS  SHOWING  THE  STRENGTH  OF  SAP-STAINED 

WOOD1. 


Species 

Mois- 
ture per- 
cent at 
time  of 
test 

Condition 

Strength  in  static  bending 

F.S.   -at 
EL. 
(pounds 
per 
square 
inch) 

M.  of  R. 
(pounds 
per 
square 
inch) 

M.  of  E. 
(1000 
pounds 
per 
square 
inch) 

Res.  to 
M.L. 

(pounds 
per 
cubic 
inch) 

Hard- 
ness 
total 
load 
pounds 

Shortleaf  pine.  .  . 
Longleaf  pine.  .  .  . 

17.7 
9.5 
8.7 
17.6 
7.32 
7.34 

Unstained 
do 
Stained 
Unstained 
do 
Stained 

6,295 
7,729 
8,902 
7,322 
10,932 
11,295 

10,040 
13,736 
14,081 
11,679 
16,759 
17,858 

1,559 
1,792 
1,883 
1,785 
2,187 
2,374 

9.6 

9.8 
9.4 
8.5 
11.97 
11.77 

857 
954 
852 
772 
910 
883 

They  show  that  for  the  same  moisture  content  the  heavily  stained 
shortleaf  pine  was  slightly  weaker,  less  tough,  and  showed  less 
surface  hardness  than  the  unstained.  In  the  longleaf  pine,  which 

1  Circular  192,  U.  S.  Forest  Service,  "The  Prevention  of  Sap  Stain  in 
Lumber,"  by  Howard  F.  Weiss  and  Charles  T.  Barnum. 


30          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

was  only  slightly  stained,  the  differences  in  strength,  toughness, 
and  hardness  between  stained  and  unstained  boards  were  too 
slight  to  be  noticed.  Immense  numbers  of  minute  spores  soon 
form  on  the  freshly  cut  sapwood  and  are  blown  by  the  wind  like 
dust  until  they  alight  on  other  wood,  when  they  start  to  germ- 
inate. It  is  chiefly  in  this  way  that  the  stain  is  spread  and  be- 
cause of  the  enormous  numbers  of  spores  produced,  lumber 
cut  during  the  warmer  months  has  little  chance  of  drying  without 
being  attacked.  So  far,  then,  as  this  cause  is  concerned,  we  may 
consider  sap  stain  as  analogous  to  decay,  but  the  results  as  shown 
above  are  decidedly  different. 


I 
I   . 


*     J* 

CHAPTER  III 

THE  EFFECT  OF  THE  STRUCTURE  OF  WOOD  UPON  ITS 
INJECTION  WITH  PRESERVATIVES 

The  Effect  of  Density  upon  Absorption. — It  is  well  known  that 
the  structure  of  wood  has  a  very  pronounced  effect  upon  the 
manner  in  which  preservatives  can  be  injected  into  it,  so  that 
all  kinds  of  wood  cannot  be  handled  in  the  same  way  and  uni- 
form results  secured.  It  is  the  purpose  of  this  chapter  to  show 
the  effect  of  the  various  structures  so  far  as  they  are  known  upon 
the  diffusion  of  the  preservatives,  without  going  into  a  detailed 
discussion  of  wood  formation  and  composition. 

For  our  purposes  we  may  consider  wood  as  being  composed 
of  a  mass  of  small,  hollow  fibers  or  cells  of  various  sizes  and 
forms  more  or  less  closely  packed  together.  The  materials  of 
which  they  are  composed  are  chiefly  cellulose  and  lignin.  These 
substances,  in  themselves,  are  heavier  than  water,  so  that,  were 
the  cells  solid,  the  wood  would  sink  in  water.  The  weight  or 
density  of  wood  is  largely  dependent  upon  the  amount  of  air 
space  in  the  various  cells  and  it  is  this  confined  air  which  gives 
wood  its  buoyancy.  Thus  in  woods  like  ebony  or  hickory  the 
cells  are  dense  and  the  air  spaces  small  so  that  a  cubic  foot  of 
such  wood  contains  a  large  percentage  of  solid  wood  substance. 
In  other  varieties  like  white  pine  or  cedar  the  cells  have  larger 
air  spaces  and  there  is  a  smaller  percentage  of  solid  wood  sub- 
stance so  that  the  wood  is  light  and  will  readily  float  in  water. 
Painstaking  research  has  shown  that  the  density  of  wood  sub- 
stance irrespective  of  species  is  practically  the  same,  being 
about  1.55  specific  gravity,  or  about  97  pounds  per  cubic  foot. 

It  would  appear  that  woods  which  are  light  in  weight  and 
hence  have  considerable  air  space  would  absorb  preservatives 
more  readily  than  woods  which  are  heavy.  Such,  however,  is 
not  the  case,  hence  the  ability  of  wood  to  absorb  preservative 
cannot  be  judged  from  its  density  or  weight.  In  other  words, 
the  resistance  of  wood  to  injection  with  preservatives  has  little  to  do 

31 


32          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

with  the  dry  weight  of  the  wood.  This  is  an  important  fact  on 
which  many  writers  and  engineers  have  been  lead  astray.  Under 
identical  conditions  of  test  white  spruce  heartwood  which  weighed 
oven-dry  25  pounds  per  cubic  foot  absorbed  only  6  pounds  of 
creosote  per  cubic  foot,  while  heart  longleaf  pine  weighing  39 
pounds  absorbed  13  pounds  of  the  oil.  Numerous  other  ex- 
amples could  be  given  which  prove  this  beyond  all  reasonable 
doubt.  There  seems,  however,  to  be  a  rather  direct  relation 
between  density  and  absorption  in  wood  of  the  same  species. 
Thus  red  oak,  for  example,  which  is  comparatively  light  in 
weight,  will  absorb  more  preservative  than  red  oak  which  is 
heavy.  The  difference  is  not  great  and  has  little  practical  sig- 
nificance. Similar  observations  have  been  made  on  maple.1 
Whether  or  not  the  relationship  will  hold  for  all  species  cannot 
be  stated.  As  the  dry  weight  of  certain  woods  depends  on  the 
rate  at  which  the  woods  have  grown,  a  relationship  between 
absorption  and  rate  of  growth  can  be  said  to  exist,  although  this 
is  not  strongly  defined. 

Absorption  by  the  Cell  Walls. — It  has  been  held  that  the  cell 
walls  of  wood  do  not  absorb  creosote,  hence  the  amount  of  this 
oil  which  can  be  impregnated  into  wood  depends  upon  the  amount 
of  air  space  which  the  wood  contains.  This  claim  is  not  strictly 
true.  Tests  made  at  the  Forest  Products  Laboratory  show  that 
the  cell  walls  are  capable  of  absorbing  creosote  although  the 
amount  is  very  small  and  of  little  significance  in  practical  opera- 
tions.2 In  these  tests  a  number  of  pieces  of  hard  maple,  yew  and 
hemlock,23/4  X3/4X  1/8  inch  were  dried  in  an  oven  at  212°  F.  for 
24  hours  then  placed  in  a  desiccator  and  weighed  when  cold  to 
the  nearest  0.001  gram.  The  volume  of  each  piece  was  then  deter- 
mined by  displacement  and  the  specimens  impregnated  with 
water-free  creosote  for  1  hour  under  a  pressure  of  250  pounds 
per  square  inch  and  temperature  of  175°  F.  The  volumes  of  the 
pieces  after  treatment  were  then  determined  and  compared  with 
the  volumes  at  the  same  temperatures  before  treatment. 

The  average  increases  in  volume  resulting  from  the  treatments 
of  the  three  species  in  percent  of  the  volumes  before  treatment 
were: 

1  Bulletin  126,  U.  S.  Forest  Service,  "Experiments  in  the  Preservative 
Treatment  of  Red  Oak  and  Hard  Maple  Cross-ties."     F.  M.  Bond,  1913. 

2  Circular  200,  U.  S.  Forest  Service,  "The  Absorption  of  Creosote  by  the 
Cell  Walls  of  Wood,"  by  C.  H.  Teesdale. 


THE  EFFECT  OF  THE  STRUCTURE  OF  WOOD 


33 


Percent 

Yew,  heartwood 6.81 

Yew,  sapwood 10.70 

Hemlock,  heartwood . . .  J  .  t 7.30 

Hard  maple,  heartwood.  ^ 8.14 

The  Effect  of  Sapwood  and  Heartwood  upon  Injection. — The 

sapwood  is  commonly  defined  as  that  portion  of  the  tree  in  which 
the  wood  cells  are  alive  and  perform  vital  functions.  It  always 
occurs  immediately  under  the  bark  and  can  usually  be  distinguished 
from  the  heartwood  by  the  lighter  color.  The  width  of  the  sap- 
wood  varies  considerably  in  the  different  kinds  of  wood,  being 
very  narrow  in  such  varieties  as  chestnut  or  black  locust  and  wide 
in  others  like  loblolly  pine  and  red  gum.  This  difference  has  a 
very  direct  bearing  on  the  treatment  of  wood,  because  the  sap- 
wood  of  all  species  can  be  readily  impregnated  with  preservatives. 
In  some  varieties  the  sapwood  is  easy  to  inject  while  the  heart- 
wood  is  practically  impenetrable.  This  is  typified  by  the  red  gum 
and  Douglas  fir.  In  other  woods  like  hemlock,  there  is  little 
difference  between  the  resistance  to  penetration  offered  by  the 
sap  and  heartwood.  These  differences  are  often  very  marked,  as 
is  shown  in  Table  3.  The  specimens  of  wood  were  selected  from 
various  species,  dried  to  the  same  degree  of  moisture,  and  all 
impregnated  at  the  same  time  in  a  treating  cylinder  at  the 
Forest  Products  Laboratory  by  the  full-cell  creosote  process. 

TABLE  3. — THE  ABSORPTION  OF  COAL-TAR  CREOSOTE  BY  THE  HEART-WOOD 

AND   SAPWOOD   OF   VARIOUS   WOODS  GIVEN  EXACTLY  THE 

SAME  TREATMENT.     (SIZE   OF   SPECIMENS    2  X  2  X  12 

INCHES;  Six   IN   EACH  TEST) 


Kind  of  wood 

Average  absorption  of  creosote,  pounds 
per  cubic  foot 

Heartwood 

Sapwood 

Douglas  fir 

4.38 

14.46 

West,  yellow  pine  

16.14 

28.74 

Longleaf  pine  .... 

12.90 

34.20 

Lodgepole  pine  

12.84 

31.56 

Eastern  hemlock  1                17.28 

18.78 

Alpine  fir  

3.66 

4.14 

White  spruce  

6.42 

8.22 

34          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

The  reason  why  sapwood  as  a  rule  is  more  permeable  to  the 
passage  of  preservatives  is  not  definitely  known.  So  far  as 
the  size,  shape  and  strength  of  the  cells  are  concerned  there  is 
little  difference  between  those  in  the  sapwood  and  those  in  the 
heartwood.  It  is  quite  likely,  therefore,  that  the  reason  must 
be  looked  for  in  changes  which  occur  in  the  composition  of  the 
cell  walls  when  they  are  transformed  into  heartwood  cells,  or 
in  the  cell  contents  or  in  the  character  of  the  pits  in  the  cell 
walls  which  become  changed  in  position  and  more  or  less  per- 
manently set.  Much  further  work  remains  to  be  done  before  the 
true  cause  is  determined. 

The  Effect  of  Summerwood  and  Springwood  upon  Injection. — 
All  of  the  commercially  important  American  woods  grow  by 
adding  a  successive  layer  of  wood  with  each  successive  year  of 
life.  These  layers  are  concentric  and  are  called  "annual  rings." 
Normally,  one  such  annual  ring  or  layer  is  produced  each  year, 
so  by  counting  the  number  of  such  rings  from  the  center  to  the 
outside  of  a  piece  of  wood,  the  number  of  years  it  took  to  grow 
the  wood  can  be  directly  determined.  In  most  varieties  of  trees 
there  is  a  vast  difference  between  the  character  of  the  wood 
in  the  annual  ring  formed  in  the  spring  and  that  formed  in  the 
summer.  The  former  is  called  ' '  spring  wood/ '  the  latter  { '  summer- 
wood."  Thus  in  longleaf  pine,  for  example,  the  cells  in  the 
spring  wood  have  much  thinner  walls  than  those  in  the  summer- 
wood.  This  of  course  makes  the  springwood  much  lighter  and 
weaker  than  the  summerwood  and  causes  the  banded  appearance 
so  noticeable  in  edge  or  "comb-grained "  yellow  pine  lumber.  In 
other  coniferous  woods  like  white  spruce  the  difference  in  the  cells 
of  the  spring  and  summerwood  is  not  so  pronounced  and  hence 
such  wood  is  much  more  uniform.  The  same  differences  occur  in 
certain  hardwoods  like  oak,  ash,  etc.,  where  many  of  the  cells  in 
the  springwood  are  so  large  as  to  be  called  "pores"  or  "vessels." 
In  other  hardwoods  like  the  maple,  beech,  birch,  etc.,  the  dif- 
ference between  the  spring  and  summerwood  is  slight  and  hence 
these  woods  possess  greater  uniformity.  In  all  woods  which  have 
no  marked  difference  in  the  spring  and  summerwood  the  injec- 
tion of  preservatives  is  fairly  uniform  throughout  the  entire  annual 
ring.  The  beech,  maples,  firs,  spruces,  etc.,  fall  in  this  class. 
(See  Plate  IV,  Fig.  D.)  Great  irregularity  in  penetration  and 
absorption  occurs  in  the  other  types  of  wood.  Thus  in  longleaf 
pine,  red  oak,  ash,  etc.,  the  treatment  will  often  appear  in  bands 


PLATE  IV 


FIG.  A. — Longleaf  pine  boards  piled  solidly  after  one  month's  exposure  to 
sap  stain  fungi.  Boards  on  left,  untreated;  boards  on  right  dipped  in  a  weak 
solution  of  mercuric  chloride.  Note  absence  of  stain.  (Forest  Service 
photo.) 


Fig.  B. — Cross  section  through  red  oak — a  "ring  porous"  wood.  Note 
arrangement  of  pores  mostly  in  the  spring  wood.  Note  also  clearness  of 
pores.  X50.  (Forest  Service  photo.) 

(Facing  page  34.) 


PLATE  IV 


FIG.  C. — Cross  section  through  maple — a  ''diffuse  porous"  wood.  Note 
pores  scattered  through  entire  width  of  annual  ring.  X50.  (Forest  Service 
photo.) 


FIG.  D. — Cross  section  through  spruce — a  "nonporous"  wood.  Note 
absence  of  pores.  Larger  openings  are  "resin  ducts"  or  cells.  X  50. 
(Forest  Service  photo.) 


FIG.  E. — Cross  section  through  white  oak.     Note  pores  clogged  with  "ty- 
loses."     Compare    with    red    oak.      X  50.     (Forest    Service    photo.) 


FIG.  F. — Radial  section  through  pine.  Note  bordered  pits  or  "eyes,"  also 
how  fibers  fit  into  one  another.  Vertical  cells  on  extreme  left  are  medullary 
or  "pith  ray"  cells.  X  250.  (Forest  Service  photo.) 


THE  EFFECT  OF  THE  STRUCTURE  OF  WOOD      35 

(in  a  cross  section  view)  or  streaks  (in  a  radial  view) .  This  is 
because  the  spring  and  summerwood  offer  different  resistances  to 
the  passage  of  the  preservative.-  In  red  oak  and  ash  most  of  the 
preservative  will  be  found  in  the  springwood,  while  in  longleaf 
pine  most  of  it  occurs  in  the  aense  summerwood.  The  exact 
reasons  why  these  differences  occur  will  be  described  further 
on.  It  follows,  therefore,  that  the  rate  at  which  certain  woods 
grow  affects  very  appreciably  the  uniformity  of  the  treatment 
secured.  When  the  tree  grows  rapidly,  the  annual  rings  are 
comparatively  wide,  hence  the  bands  of  heavy  and  light  treated 
wood  are  pronounced.  (See  Plate  V,  Fig.  A.)  When  growth  has 
been  slow  these  rings  are  narrower  and  the  bands  are  much 
less  pronounced.  (See  Plate  V,  Fig.  B.)  In  general,  therefore,  the 
species  which  have  pronounced  differences  in  the  spring  and  sum- 
merwood have  a  much  greater  irregularity  in  the  treatment  of 
the  annual  rings  than  those  which  are  of  a  more  uniform 
stucture,  especially  when  of  rapid  growth.  It  is  largely  because 
of  these  differences  that  the  number  of  rings  per  inch  allowed 
in  certain  classes  of  material,  such  as  paving  blocks,  is  specified. 

The  Effect  of  Vessels  or  "Pores"  on  the  Treatment  of  Wood. — 
All  varieties  of  American  " hardwoods"  possess  elongated  cells 
called  " vessels"  or  " pores."  These  are  characteristic  of  hard- 
woods and  form  a  reliable  means  of  distinguishing  such  woods 
from  the  " conifers"  in  which  the  vessels  are  entirely  absent. 
These  pores  occur  in  two  ways:  first,  scattered  through  the  annual 
rings,  and  second,  as  bands  of  "rings"  in  the  springwood  of  the 
annual  ring.  Because  of  this  difference  the  hardwoods  are 
commonly  classified  as  diffuse  porous  (maple,  birch,  beech,  etc.) 
and  ring  porous  (oak,  ash,  hickory,  etc.).  These  pores,  which 
are  often  so  long  as  to  resemble  capillary  tubes,  are  easily  filled 
with  preservative  and  offer  ready  channels  for  conducting  the 
preservative  into  the  wood.1  Thus  in  red  oak  the  pores  are  so 
long  that  it  is  possible  to  blow  through  a  piece  of  this  wood  4 
feet  or  more  in  length.  It  can  be  easily  understood,  therefore, 
why  such  woods  readily  absorb  preservatives  and  why  the 
character  of  the  treatment  secured  depends  so  much  upon  the 
arrangement  of  the  pores. 

The  Effect  of  Tyloses  on  the  Treatment  of  Wood.— It  frequently 
happens  that  the  vessels  described  above  are  clogged  with  a  cell 

1  When  the  pores  are  filled  with  "tyloses"  this  statement  does  not  hold. 
See  discussion  under  "tyloses." 


36          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

growth  which  prevents  the  passage  of  air  or  liquids  through  them. 
This  growth  is  characteristic  of  certain  kinds  of  wood  like  white 
oak  and  black  locust  and  renders  them  practically  impervious  to 
absorption.  It  is  caused  by  cells,  called  "tyloses,"  growing  into 
the  vessels.  (See  Plate  IV,  Fig.  E.)  These  may  occur  even  in  the 
sapwood  and  when  they  are  present  the  vessels  cannot  be  pene- 
trated. In  some  kinds  of  wood  like  white  oak,  tyloses  are  uni- 
form throughout,  only  a  few  vessels  being  without  them.  In 
other  varieties,  like  black  oak,  tyloses  occur  irregularly  through 
the  wood.  Thus  in  certain  parts  of  a  stick  the  vessels  may  be 
few  and  the  preservative  will  readily  enter,  while  in  another  part 
the  tyloses  may  fill  the  vessels  and  absolutely  prevent  any 
entrance  of  the  preservative.  In  such  cases  a  very  irregular 
diffusion  of  the  preservative  naturally  occurs.  There  is  no  way 
of  telling  to  what  extent  the  tyloses  occur  in  these  woods  ex- 
cept by  a  careful  microscopic  examination.  From  a  large  num- 
ber of  microscopic  examinations  of  various  American  woods  it 
is  possible  to  class  them  into  three  groups  depending  upon  the 
presence  or  absence  of  tyloses.1 

Group  1 — Tyloses  absent — the  maples,  birches,  blue  beech, 
flowering  dogwood,  holly,  silverbell,  black  and  water  gums, 
black  and  red  cherry,  basswood,  persimmon,  honey  locust. 

Group  2 — Tyloses  few — yellow  buckeye,  beech,  red  gum  (sap), 
yellow  poplar,  magnolias,  sycamore,  black  cottonwood,  eucal- 
yptus (blue  gum),  white  and  Oregon  ashes,  and  the  elms. 

Group  3 — Tyloses  abundant — large  tooth  aspen,  hardy  catalpa, 
desert  willow,  green,  pumpkin  and  blue  ash,  mockernut,  water 
pignut,  shellbark,  bitternut,  nutmeg  and  shagbark  hickories, 
butternut,  black  walnut,  red  mulberry,  blackjack,  white,  Garry, 
overcup,  valley,  burr,  cow,  post  and  swamp  white  oaks,  black 
locust,  and  osage  orange. 

Tyloses  were  also  found  very  scatteringly  in  the  pines,  but  in  no 
other  conifers  examined. 

The  Effect  of  Resin  Ducts  on  the  Treatment  of  Wood.— As 
mentioned  above,  conifers  do  not  possess  vessels  or  pores.  Some 
of  them  do,  however,  have  a  structure  which,  so  far  as  a  penetra- 
tion with  preservatives  is  concerned,  functions  like  pores.  This 
structure  is  called  a  " resin  duct,"  and  as  the  name  implies,  it  is 
a  duct  or  "  pore  "  usually  producing  and  containing  resin.  Except 
when  the  ducts  are  clogged  with  resin  or  some  other  obstruction, 

1  From  examinations  by  Eloise  Gerry,  U.  S.  Forest  Products  Laboratory. 


PLATE  V 


FIG.  A.— Cross  section  through  a  lolbolly  pine  tie.  Note  wide  rings 
showing  rapid  growth,  also  note  sharp  transition  of  spring  wood  and 
summerwood. 


FIG.  B. — Cross  sections  through  two  long  leafpine  stringers.  Note 
narrow  rings  especially  in  sapwood,  showing  slow  growth.  (Forest  Service 
photo.) 

(Facing  page  36.) 


PLATE  V 


m *•*••• 

If  If  ft' I- 

lP~  -        .* 


t    « 


FIG.  C. — Cross  section  through  the  summerwood  of  larch  (greatly  magni- 
fied) showing  slits  in  cell  walls.     (Forest  Service  photo.) 


FIG.  D. — Showing  ease  with  which  chestnut  peels  in  the  spring.     (Author's 

photo.) 


THE  EFFECT  OF  THE  STRUCTURE  OF  WOOD      37 

they  afford  channels  for  the  ready  penetration  of  the  preserva- 
tive. Some  experiments  have  been  made  at  the  U.  S.  Forest 
Products  Laboratory  to  determine  the  effect  of  resin  in  the 
ducts  upon  the  entrance  of  coal^ar  creosote.  It  was  found  that 
such  resin,  particularly"  when  it  is  old,  has  a  very  marked  effect 
in  retarding  the  entrance  of  the  oil.  When  the  test  blocks  of 
wood  were  first  extracted  with  a  resin  solvent  and  then  dried,  the 
creosote  entered  the  wood  very  easily. 

The  position  of  the  resin  ducts  in  the  wood  affects  very  materi- 
ally the  character  of  the  treatment.  Thus,  in  longleaf  and  lob- 
lolly pines  the  resin  ducts  are  largely  in  the  summerwood  and 
because  of  this  the  summerwood  is  more  penetrable  than  the 
springwood  even  though  it  is  much  denser.  Some  exacting 
tests  have  been  made  by  C.  H.  Teesdale  to  secure  definite  in- 
formation on  this  point.  Pieces  of  the  summerwood  of  loblolly 
pine  which  had  a  specific  gravity  of  0.95  and  pieces  of  springwood 
cut  from  the  same  specimens  which  had  a  specific  gravity  of 
0.39  were  impregnated  at  the  same  time  with  coal-tar  creosote. 
The  summerwood  absorbed  1.8  times  as  much  creosote  as  the 
springwood.  There  is  little  doubt  but  what  the  resin  ducts  had 
much  to  do  with  this  difference  and  it  is  largely  because  of  them 
that  longleaf  pine  paving  blocks  often  show  a  " banded"  treat- 
ment. In  redwood  the  ducts  occur  mostly  in  the  springwood  and 
in  this  species  a  better  absorption  and  penetration  of  preservative 
is  secured  in  the  springwood  than  in  the  summerwood. 

The  resin  ducts  also  occur  in  certain  species  in  the  medullary 
or  pith  rays.  These  are  layers  of  cells  which  radiate  from  the 
circumference  of  the  tree  to  the  center.  In  all  coniferous  woods 
which  possess  such  ducts,  good  radial  penetration  of  the  preserva- 
tive is  secured  (from  the  outside  toward  the  center).  This  fact 
is  of  considerable  importance  commercially  because  in  order  to 
secure  good  treatments,  especially  in  round  timbers  like  poles  or 
piles,  it  is  essential  to  peel  all  of  the  bark  off  them;  otherwise 
the  ends  of  the  ducts  will  be  plugged  by  the  bark  and  little  or 
no  penetration  at  that  point  secured.  It  is  believed  that  care- 
lessness in  peeling  such  woods  is  one  cause  of  the  rapid  destruc- 
tion of  creosoted  piling,  as  it  leaves  streaks  of  untreated  wood 
extending  to  the  interior  of  the  stick  and  thus  affords  avenues  of 
attack  by  marine  borers.  Pieces  of  wood  2  X  4  X  25  inches 
were  impregnated  by  Teesdale  with  coal-tar  creosote  under 
identical  conditions.  Those  which  contained  radial  resin  ducts 


38          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

were  penetrated  radially  from  one-fourth  to  three-fourths  as 
far  as  they  were  longitudinally.  In  those  woods  which  had 
no  radial  ducts,  the  radial  penetration  varied  from  one- 
twentieth  to  one  one-hundred  twentieth  of  the  longitudinal 
penetration.  Practically  all  of  the  pines  belong  to  the  former 
class,  while  many  of  the  larches,  firs,  hemlocks,  and  spruces 
belong  to  the  latter. 

The  Effect  of  Pits  upon  Injection. — The  penetration  of  pre- 
servatives in  woods  containing  vessels  and  resin  ducts  can  largely 
be  explained  by  their  presence.  In  certain  woods,  however, 
where  neither  of  these  are  present  or  where  they  are  restricted, 

the  manner  in  which  penetration 
occurs  is  not  easy  of  explanation. 
According  to  Bailey,1 "  whenever  pre- 
servatives are  injected  rapidly  into 
green  or  seasoned  wood,  the  pene- 
tration takes  place  primarily  through 
the  cavities  of  the  cells,  and  the  pre- 
servatives pass  from  one  cell  to  an- 
other through  the  bordered  pits." 
These  bordered  pits  may  be  likened 

FIG.  4 .  —  Diagrammatic  to  microscopic  "  valves  "  occurring  in 
drawing  of  pit  membrane  the  walls  of  the  cells.  (See  Plate  IV, 

tTotTrom Sfey.rri°ra-       Fi^  ^     Wh<*  the  Cells  ^  ^  aS 

in  sapwood,  the  passage  of  liquids 

through  the  pits  is  more  or  less  controlled  by  the  "torus," 
which  is  a  thickening  of  the  middle  portion  of  the  cell  wall. 
When  the  cells  are  dead,  as  in  heartwood,  the  torus  ceases  to 
move  and  frequently  becomes  fastened  to  the  pit,  thus  more  or 
less  effectively  closing  the  opening  to  the  passage  of  liquids. 
Bailey  further  states  that  the  membranes  of  the  bordered  pits 
are  not  always  entire  but  possess  numerous  minute  perforations 
(Fig.  4).  "In  green  wood  the  bordered  pits  and  membranes  are 
very  permeable  to  aqueous  solutions,  but  are  comparatively 
impervious  to  undissolved  gases  and  to  oils.  This  is  due  to 
capillary  or  surface  tension  phenomena  and  the  valve-like  action 
of  the  torus."  The  experiments  of  this  investigator  throw  much 
valuable  light  upon  the  perplexing  problem  of  the  penetration  of 
wood  and  account  for  some  of  the  results  secured  in  its  treatment. 

1  The  Preservative  Treatment  of  Wood,"  by  Irving  W.  Bailey,  Harvard 
School  of  Forestry,  1913. 


-  *%lili,rt»f.l»V>*^ 


THE  EFFECT  OF  THE  STRUCTURE  OF  WOOD      39 

The  Effect  of  Cell  Slits  upon  Penetration. — Experiments  con- 
ducted by  Tiemann  of  the  U.  S.  Forest  Products  Laboratory1 
show  that  the  walls  of  wood  ceils  frequently  slit  open  in  drying. 
These  slits  as  a  rule  are  more  discernible  in  thick- walled  cells 
than  in  thin- walled  cells.  (See  Plate  V,  Fig.  C.)  Their  presence 
has  been  advanced  by  Tiemann  and  the  author  a  a  possible  means 
of  aiding  certain  liquids  to  penetrate  wood  substance,  because  they 
furnish  points  of  weakness  in  the  cell  wall. 

The  Effect  of  the  Chemical  Composition  of  the  Cell  Wall 
upon  Absorption. — All  the  phenomena  noted  above  relate  to  the 
physical  structure  of  wood  in  relation  to  its  absorption  of  liquids. 
In  addition  to  them,  it  is  probable,  although  by  no  means  proven 
as  yet,  that  the  composition  of  the  cell  walls  in  various  woods 
exerts  a  strong  influence  upon  the  manner  in  which  they  absorb 
preservatives.  Thus,  when  the  walls  are  reenforced  by  subse- 
quent deposits  of  wood  substance,  it  is  quite  likely  that  a  dif- 
ferent effect  is  produced  than  where  no  such  thickening  occurs. 
In  addition,  the  chemical  composition  of  the  various  layers  may 
be  different,  as  well  as  the  character  of  the  materials  deposited 
upon  them.  Their  combined  action,  therefore,  in  retarding 
oils  and  water  solutions  may  be  a  variable  one,  and  hence  the 
character  of  the  absorbtion  and  penetration  obtained  may  also 
vary.  To  just  what  extent  this  is  true  is  not  known.  This 
problem  still  furnishes  a  fertile  field  for  original  research. 

It  can  be  seen  from  the  above  discussion  that  the  manner  in 
which  preservatives  penetrate  wood  is  very  complex.  No  single 
factor  in  itself  entirely  explains  it,  so  it  can  be  accounted  for  only 
by  taking  several  or  all  of  them  into  consideration. 

1  Bulletin  120,  American  Railway  Engineering  Association,  1911. 


CHAPTER  IV 

THE  PREPARATION  OF  TIMBER  FOR  ITS  PRESERVA- 
TIVE TREATMENT 

The  Cutting  Season. — There  has  been  much  discussion  con- 
cerning the  effect  of  cutting  timber  in  various  seasons  upon  its 
durability.  The  consensus  of  opinion  gives  preference  to  winter. 
This  is  undoubtedly  correct  in  that  timber  cut  at  this  period 
is  more  liable  to  be  in  better  condition  than  that  cut  at  any  other 
season.  In  so  far  as  the  contents  of  the  wood  cells  are  con- 
cerned, timber  cut  in  winter,  as  a  rule,  contains  its  largest  per- 
centage of  organic  materials,  such  as  starch,  these  being  stored 
in  the  cells  as  available  plant  food  for  the  next  spring.  These 
organic  materials  are  also  readily  attacked  by  wood-destroy- 
ing organisms  so  that  a  given  amount  of  winter  cut  wood,  other 
things  being  equal,  contains  more  food  material  for  these  de- 
structive agents  than  wood  cut  at  other  times  of  the  year. 

On  the  other  hand,  wood  cut  in  winter  is  least  subject  to  im- 
mediate insect  and  fungous  attack  because,  during  winter,  insect 
and  fungous  activities  are  at  a  minimum.  Moreover,  freshly 
cut  wood  is  less  able  to  offer  resistance  to  the  attacks  of  these 
agents  than  thoroughly  seasoned  wood. 

Aside  from  danger  from  insect  and  fungous  attack,  the  problem 
of  seasoning  is  also  of  great  moment,  and,  as  will  be  shown  later 
on,  wood  cut  during  spring,  summer,  and  early  autumn  dries 
much  more  rapidly  than  wood  cut  in  winter.  This  rapid  drying, 
unless  it  is  properly  safeguarded,  will  often  cause  green  timber  to 
check  and  split,  thus  not  only  weakening  the  wood  but  also 
exposing  more  of  its  surface  to  attack. 

The  season  of  cutting  also  has  a  marked  effect  upon  the 
reproductive  power  of  the  forest,  especially  if  the  forest  is  com- 
posed of  species  that  sprout  from  the  stump,  like  most  of  our 
hardwoods.  Sprouts  from  winter  cut  stumps  are  usually  much 
more  vigorous  and  thrifty  than  those  from  stumps  cut  at  other 
seasons;  in  fact,  the  sprouting  capacity  of  stumps  can  often  be 
killed  by  cutting  timber  in  summer  or  early  fall. 

40 


THE  PREPARATION  OF  TIMBER  41 

Contrary  to  popular  belief  timber  cut  in  winter  often  con- 
tains as  much  water  and  at  times,  more  water,  than  timber  cut 
at  other  periods.  The  common  expressions  that  in  winter  the 
"sap  is  down"  and  in  summer  "up"  account  for  this  fallacy, 
whereas  in  reality  it  is  only  dormant,  so  that  if  the  tree  is  in- 
jured in  this  period  the  sap  does  not  readily  exude  from  it.  The 
author  made  some  careful  tests  along  these  lines  when  cutting 
chestnut  timber  for  poles  in  Maryland,  and  found  that  those  cut 
in  winter  actually  contained  more  water  than  those  cut  in 
summer. 

Generally  speaking,  it  is  easiest  to  remove  felled  timber  from 
the  forests  in  winter  because  of  climatic  and  labor  conditions, 
although  in  the  South,  where  no  marked  changes  occur,  this  of 
course  is  not  true.  In  certain  northern  states,  as  in  cedar  opera- 
tions in  the  Lake  Region,  it  is  almost  impossible  to  log  except  in 
winter.  Furthermore,  the  large  amount  of  timber  cut  by  farmers 
is  felled  by  them  during  the  winter  months  because  they  are  not 
then  engaged  in  caring  for  their  food  crops. 

Peeling  Timber. — Practically  all  preservative  processes  require 
the  complete  removal  of  bark  before  the  wood  can  be  successfully 
treated.  Generally,  the  best  time  to  remove  the  bark  is  im- 
mediately after  the  tree  is  felled.  In  sawed  products  the  bark 
usually  is  removed  at  the  mill  in  slabbing  the  log.  Bark  can  be  re- 
moved most  easily  in  the  spring  (see  Plate  V,  Fig.  D),  but  adheres 
tenaciously  to  the  wood  when  cut  at  other  periods.  It  is  com- 
paratively easy  for  this  reason  to  tell  timber  cut  in  the  spring. 
The  early  removal  of  the  bark  lessens  the  weight  of  the  product, 
decreases  the  danger  from  insect  and  fungous  attack,  and  causes 
the  wood  to  dry  more  rapidly.  Because  of  the  great  resistance 
of  bark  to  penetration  by  liquids,  it  is  essential  to  carefully  and 
completely  remove  it,  if  good  results  in  treatment  are  to  be 
secured.  This  is  particularly  true  for  those  woods  which  are 
penetrated  readily  in  a  radial  direction,  as  the  pines.  For  species 
like  the  tamarack,  spruce,  etc.,  whose  radial  penetration  is  small, 
this  precaution  is  not  so  essential.  The  author  has  seen  pine  pil- 
ing impregnated  with  18  pounds  of  creasote  to  the  cubic  foot  that 
had  absolutely  no  penetration  of  the  oil  under  strips  of  bark  less 
than  I/ 16  inch  in  thickness.  (See  Plate  VI,  Fig.  A.)  Theinnerbark 
or  "skin"  is  particularly  resistant,  and  it  is  believed  that  its  presence 
is  at  times  one  cause  contributing  to  the  rapid  failure  of  those 
treated  piles  which  are  destroyed  after  a  few  years'  service.  Too 


42          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

often  the  treating  engineer  counts  on  the  bark  becoming  loose 
during  the  treatment  in  the  cylinder,  and  although  this  frequently 
occurs,  nevertheless  it  often  adheres  firmly  to  the  wood  and  thus 
results  in  poor  workmanship. 

It  sometimes  happens  that  better  treatments  can  be  secured 
by  seasoning  wood  with  the  bark  on,  rather  than  with  the 
bark  off.  This  was  true  in  some  tests  made  by  the  Chicago 
and  Northwestern  Railroad  on  hemlock  and  tamarack  ties  at 
Escanaba,  Mich.  It  appeared  that  the  ties  peeled  immediately 
after  cutting  seasoned  so  rapidly  that  the  outer  layers  of  the 
wood  hardened  and  became  much  more  resistant  to  the  absorption 
of  the  preservative  than  those  in  which  the  bark  was  removed 
just  before  the  ties  were  run  into  the  treating  cylinder.  This, 
however,  is  an  exception  to  general  practice. 

Generally,  bark  is  removed  by  hand,  the  only  tools  being 
a  spud,  draw  knife,  or  axe.  There  is  a  good  opportunity  for  the 
invention  of  some  machine  that  will  economically  and  satisfactor- 
ily remove  bark  and  thus  decrease  the  labor  involved  in  present 
methods. 

Seasoning  Timber. — Wood  in  all  living  trees  contains  water. 
The  amount  of  water  thus  contained  varies  with  the  kind  of  wood, 
the  conditions  under  which  it  grew,  and  the  season.  It  fre- 
quently happens  that  in  the  sapwood,  and  sometimes  in  the  heart- 
wood,  the  weight  of  the  water  is  more  than  the  weight  of  the  wood 
substance  itself.  Thus  the  gums  when  dried  may  weigh  less 
than  half  their  weight  at  the  time  of  cutting.  In  general, 
as  soon  as  timber  is  cut  it  begins  to  lose  the  water  it  contains. 
This  loss  of  water  is  called  " seasoning/'  In  addition  to  the  loss 
of  water,  other  changes  occur,  such  as  a  fixation  or  transformation 
of  organic  and  inorganic  materials  stored  in  the  wood,  and  an 
apparent  " oxidation"  of  the  wood  substance.  The  objects  of 
seasoning  are,  in  brief: 

1.  To  prevent  injury  by  insects  and  decay  before  the  timber  is 
placed  in  service. 

2.  To  increase  the  durability  of  timber  in  service. 

3.  To  prevent  shrinking  and  checking  of  the  wood  in  service. 

4.  To  increase  the  strength  of  the  wood. 

5.  To  decrease  the  weight  of  the  wood  and  hence  reduce  shipping 
charges. 

6.  To  prepare  the  wood  for  its  injection  with  preservatives  and 
for  other  industrial  uses. 


THE  PREPARATION  OF  TIMBER  43 

It  is  well  known  that  if  wood  can  be  kept  dry  it  will  not  decay. 
House  furniture,  for  example,  under  ordinary  conditions  of  use 
will,  so  far  as  decay  is  concerned,  last  indefinitely.  It  is  solely 
because  of  their  protection  frorrypioisture  that  the  wooden  coffins 
used  by  the  Egyptians  liave  been  preserved  to  us.  Water  in 
wood  is  an  absolute  requirement  for  decay.  Wood  which  can 
be  kept  dry  will  never  decay.  Just  how  much  water  in  wood  is 
necessary  in  order  to  meet  the  requirements  of  wood-destroying 
fungi  is  not  known,  but  from  a  few  tests  which  the  author  has 
made  it  appears  that  it  is  in  general  more  than  20  percent. 

It  has  almost  unanimously  been  held  that  seasoned  wood 
placed  in  conditions  of  service  where  it  is  subject  to  decay  wil- 
last  longer  than  unseasoned  wood.  While  this  is  sometimes 
true,  nevertheless  the  importance  which  has  been  attached 
to  air  seasoning  as  a  means  in  itself  of  prolonging  the  life  of  wood 
has  probably  been  exaggerated.  Authentic  records  on  posts, 
poles,  ties,  and  mine  timbers  kept  by  the  Forest  Service  indicate 
that  there  is  little  or  no  difference  in  their  durability  whether 
they  were  placed  green  or  air  seasoned. 

If  green  timber  is  used  for  construction  purposes,  it  will  almost 
invariably  lose  water  and  hence  check,  shrink,  and  warp  more  or 
less  severely.  In  order  to  avoid  such  defects,  it  is  policy  to  use 
seasoned  wood  in  place  of  green  in  all  classes  of  construction 
where  they  prove  objectionable.  Furthermore,  wood  which 
has  been  seasoned  prior  to  injection  with  perservative  is  far  less 
liable  to  check  on  the  surface  and  thus  expose  the  untreated 
wood. 

The  effect  of  water  in  wood  upon  its  strength  is  discussed  in 
Chapter  XVIII.  The  decrease  in  weight  due  to  seasoning  is  so 
large  as  to  warrant  holding  the  timber  until  seasoned  before  ship- 
ment is  made.  This  fact  is  now  so  well  recognized  that  it  has  be- 
come common  practice,  but  on  account  of  unfavorable  conditions 
surrounding  the  seasoning  of  wood  at  the  place  where  it  is  cut,  the 
shipment  of  green  material  is  sometimes  imperative.  A  single 
carload  of  30-foot  chestnut  poles  if  shipped  seasoned  rather  than 
green  would  save  at  least  150  pounds  of  freight  per  pole,  or, 
counting  50  poles  per  car,  a  total  of  7500  pounds.  This  saving 
even  on  short  hauls  often  more  than  pays  for  the  cost  of  seasoning 
the  poles  and  holding  them  in  storage  awaiting  shipment.  What 
is  true  for  poles  is  true  even  to  a  greater  extent  for  smaller 
products  because  they  season  more  thoroughly. 


44          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

It  is  in  the  preparation  of  wood  for  injection  with  preservatives 
that  seasoning  plays  a  very  important  part,  as  it  is  quite  essential 
to  remove  some  or  most  of  the  water  from  the  wood  before  the 
preservative  can  be  injected. 

Water  may  be  considered  as  existing  in  wood  in  two  forms:  (1) 
as  "free  water"  in  the  cell  cavities  and  (2)  as  "confined  water" 
in  the  cell  walls.  When  wood  begins  to  season  it  is  the  free 
water  which  is  first  lost.  Wood  can  lose  all  of  this  free  water 
without  its  strength  being  affected.  Just  as  soon,  however,  as 
water  starts  to  leave  the  cell  walls  the  strength  of  wood  begins 
to  increase  very  rapidly,  and  checking,  warping,  and  splitting  are 
liable  to  occur.  The  point  where  this  occurs  has  been  called  by 
Tiemann  the  "fiber-saturation  point."  It  varies  in  the  different 
species  but  in  general  ranges  from  25  to  30  per  cent  moisture. 
When  the  free  water  has  left  the  wood,  the  wood  of  course  con- 
tains a  larger  air  space  or  volume  which  can  later  be  occupied  by  a 
preservative  like  creosote.  This  may  be  illustrated  as  follows: 
Assume  the  oven-dry  weight  of  shortleaf  pine  is  32  pounds  per 
cubic  foot,  that  solid  wood  substance  weighs  97  pounds  per 
cubic  foot,  that  green  shortleaf  pine  contains  21  pounds  of  water 
per  cubic  foot;  then  about  two-thirds  of  a  cubic  foot  of  green 
pine  would  be  wood  substance  and  water,  leaving  about  one- 
third  of  the  volume  air  space.  If,  now,  all  the  free  water  were 
removed,  almost  two-thrds  of  the  cubic  foot  of  wood  would  be 
air  space  capable  of  occupancy  by  the  preservative. 

Aside  from  the  loss  of  water  which  takes  place  in  seasoning, 
other  changes  occur.  The  bordered  pits  become  more  or  less 
ruptured,  or  changed  in  position,  so  that  passage  of  liquids 
through  them  is  facilitated  or  retarded.  Furthermore,  the  wood 
cells  frequently  check  as  well  as  the  surface  of  the  wood.  As  a 
result  of  these  changes  which  occur  in  seasoning  wood,  practically 
all  processes  now  call  for  some  kind  of  a  seasoning  treatment 
before  the  preservative  is  injected.  The  chief  exception  occurs 
in  the  Boucherizing  process,  which  is  at  present  of  no  com- 
mercial importance  in  the  United  States.  Five  methods  of 
seasoning  wood  are  now  practised :  Open-air  seasoning,  seasoning 
in  hot  air,  seasoning  in  saturated  and  superheated  steam,  and 
seasoning  in  oil. 

Open-air  Seasoning. — Open-air  seasoning,  as  the  term  implies, 
consists  simply  in  piling  the  timber  out  of  doors  where  it  is 
exposed  to  the  atmosphere.  When  its  moisture  content  reaches 


THE  PREPARATION  OF  TIMBER  45 

an  equilibrium  with  the  atmospheric  moisture,  the  wood  is  said 
to  be  "air  seasoned."  It  can  thus  be  seen  that  the  amount  of 
water  in  air-seasoned  wood  varies  considerably.  Thin  pieces  of 
wood  2  inches  or  less  in  thickness  in  our  northern  climates, 
when  air  seasoned,  contain  aoout  10  to.  15  percent  of  water. 
Thicker  pieces  like  poles,  ties,  etc.,  are,  under  the  same 
conditions,  "air  seasoned"  when  they  contain  25  to  35  percent  of 
water.  Some  Douglas  fir  bridge  stringers  8  inches  X  16  inches 
in  cross  section  contained  over  25  percent  of  moisture  after  being 
exposed  to  the  atmosphere  for  2  years. 

The  open-air  seasoning  of  wood  is  the  method  most  commonly 
practised  in  the  United  States  to  prepare  it  for  injection  with 
preservatives.  It  is  cheap,  safe  to  operate,  and  very  efficient. 
The  chief  objections  to  it  are  the  long  length  of  time  the  wood 
must  be  held  before  it  seasons,  thus  tying  up  capital  in  wood 
and  yardage,  and  dangers  from  fire,  insects,  and  decay  while 
stored  during  the  seasoning  period.  In  some  parts  of  our 
country  where  the  climate  is  warm  and  damp  it  is  impossible  to 
air-season  certain  woods  without  having  them  attacked  by 
incipient  decay.  Other  objections  to  air  seasoning  are  an  inability 
to  fill  "rush  orders"  and  injury  from  checking,  although  this 
latter  objection  can  be  largely  overcome  by  proper  methods  of 
piling. 

To  most  efficiently  season  wood  in  the  open  air,  it  is  necessary 
to  subject  it  to  a  free  circulation  of  air.  Stagnant  air  is  very 
prone  to  foster  decay.  The  seasoning  yards  should,  therefore, 
be  in  situations  exposed  to  the  sun  and  wind.  All  of  the  timber 
should  be  raised  off  the  ground  and  should  be  piled  as  openly  as 
possible  without  producing  too  rapid  drying,  which  might  result 
in  serious  checking  or  splitting.  Another  precaution  is  to  keep 
the  yard  free  from  water,  vegetation,  and  decaying  wood. 

The  rate  at  which  wood  seasons  depends  upon  many  factors, 
chief  of  which  is  the  time  of  the  year.  Spring  and  summer  are 
in  general  the  two  periods  when  most  rapid  seasoning  occurs. 
More  detailed  information  for  the  various  forest  products  is  given 
in  the  following  pages  under  the  discussion  of  these  products. 
When  wood  has  once  air  seasoned,  any  water  which  it  might  ab- 
sorb from  rains,  for  example,  is  quickly  lost.  Air-seasoned  poles 
tested  by  the  author  absorbed  15  pounds  of  water  during  a 
thunderstorm  but  lost  all  of  it  within  24  hours  after  the  rain 
stopped.  It  is  by  no  means  necessary  to  season  wood  until  it 


46          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

has  lost  all  its  free  water  before  it  is  in  satisfactory  condition 
for  treatment.  Large  products  such  as  ties  and  poles  may  have, 
when  "  air-seasoned/'  an  average  of  30  percent  of  water,  but 
the  distribution  of  this  water  may  vary  from  5  to  10  percent 
in  the  outer  layers  of  wood  as  a  minimum  to  40  or  50  percent  in 
the  inner  layers  as  a  maximum.  If  a  tie  or  pole  is  of  such  a 
nature  (as  is  customary)  that  its  interior  cannot  be  treated 
even  if  it  is  dry,  little  or  no  advantage  is  gained  in  attempting 
to  hold  it  until  this  condition  of  uniform  dryness  is  reached. 
The  object,  therefore,  in  open-air  seasoning  should  be  to  cut 
the  period  of  drying  as  short  as  possible  without  decreasing  the 
penetration  of  the  preservative.  No  fixed  time  can  be  given 
for  this,  as  it  depends  on  too  many  variables  which  must  be 
worked  out  for  the  conditions  at  each  plant. 

Hot-air  Seasoning. — By  " hot-air  seasoning"  is  meant  kiln 
drying  the  wood.  This  method  is  now  only  practised  in  the 
United  States  on  certain  kinds  of  lumber  and  small  manu- 
factured products.  It  is  rarely  if  ever  used  for  large  products 
such  as  piles,  poles,  and  ties.  In  Europe,  however,  the  method 
is  sometimes  employed,  especially  as  a  final  drying  for  timber 
already  partly  seasoned  in  the  open  air.  It  is  felt  that  the 
method  will  not  become  common  practice  in  our  country  be- 
cause equally  as  good  if  not  better  results  can  be  secured  in 
shorter  time  and  at  less  expense  by  other  means.  The  method 
employed  in  hot-air  or  kiln  drying  consists  in  placing  the  wood 
in  a  retort  or  kiln,  where  the  air  is  usually  heated  by  means  of 
steam  coils.  Circulation  of  the  air  is  provided  for  in  various 
ways,  either  by  blowers,  or  by  cooling  the  air  on  the  sides  of 
the  kiln,  or  by  drawing  in  air  through  vents  in  the  bottom  of 
the  kiln  and  permitting  the  hot  air  to  escape  through  vents 
in  the  top.  Such  treatment  results  in  removing  the  water  from 
the  wood  in  much  shorter  time  than  open-air  seasoning  and  in 
addition  warms  the  wood  for  the  entrance  of  the  preservative. 
Wood  so  heated  is,  however,  liable  to  check  and  warp  seriously 
or  case-harden,  thus  becoming  weak  and  brash.  For  the  treat- 
ment of  small  products  of  comparatively  high  value,  this  method 
gives  very  satisfactory  results,  but  for  dimension  stock  or  products 
it  has  little  to  commend  it. 

Seasoning  in  Saturated  Steam. — Next  to  open-air  seasoning, 
seasoning  in  saturated  steam  is  in  most  extensive  use  in  the 
United  States  as  a  means  of  drying  wood  for  the  injection  of 


THE  PREPARATION  OF  TIMBER  47 

preservatives.  When  properly  done  this  method  gives  quick 
and  satisfactory  results.  Its  chief  advantages  are  the  ease, 
quickness,  and  comparative  cheapness  with  which  the  water 
can  be  drawn  from  the  wood,  the  warming  of  the  wood  prior 
to  its  impregnation,  and  the  ^sterilizing  of  the  wood.  When 
this  method  is  practised  a  large  storage  capacity  for  wood  and 
a  large  stock  on  hand  are  not  necessary.  Furthermore,  "rush 
orders"  can  be  taken  care  of  and  dangers  peculiar  to  open-air 
seasoning  are  avoided.  If  steamed  at  too  high  temperatures 
or  for  too  long  a  period,  considerable  injury  may  result  to  the 
strength  of  the  wood.  Steaming  wood,  in  itself,  does  not  re- 
move water  from  the  wood.  On  the  other  hand,  it  may  add 
water,  as  shown  in  Table  34.  In  practice,  to  remove  the  water 
a  vacuum  is  drawn.  This  lowers  the  boiling  point  of  water 
and  materially  hastens  the  rate  at  which  it  leaves  the  wood. 

Structural  timbers,  when  seasoned  for  the  injection  of  pre- 
servatives by  the  use  of  saturated  steam,  are  loaded  on  cylinder 
cars  or  "buggies"  and  run  into  the  treating  cylinder,  which  is 
then  closed  and  live  steam  admitted.  The  pressures  used  are 
about  20  to  40  pounds  per  square  inch.  The  wood  is  kept  in 
the  steam  bath  for  various  periods,  depending  upon  the  judg- 
ment of  the  operator,  and  the  kind  and  form  of  timber  he  is 
heating.  It  ranges  from  about  2  to  3  hours  for  ties  to 
10  hours  or  even  more  for  piling.  Tests  made  at  the 
U.  S.  Forest  Products  Laboratory  indicate  that  5  to  8  hours 
are  required  to  heat  ties  to  the  center  by  this  method.  After 
the  steam  bath  a  vacuum  of  24  to  26  inches  is  drawn  in  the 
cylinder  by  means  of  a  pump,  and  at  the  end  of  this  period  the 
wood  is  ready  for  injection  with  the  preservative.  The  length 
of  time  the  vacuum  is  held  varies  greatly,  but  is  usually  from 
1/2  to  2  hours.  Nothing  is  gained  by  holding  it  after  the 
wood  has  once  reached  a  temperature  below  which  no  further 
heat  units  leave  the  wood. 

Seasoning  in  Superheated  Steam. — It  will  be  noted  that 
seasoning  in  saturated  steam  necessitates  a  vacuum  in  order  to 
remove  the  water  from  the  wood.  With  superheated  steam 
this  is  not  necessary,  as  it  is  capable  of  absorbing  the  water 
vapor  driven  off  from  the  wood  as  fast  as  it  is  formed.  Some 
of  the  early  wood-preserving  plants  were  equipped  with  super- 
heaters, but  on  account  of  the  unskilled  labor  generally  em- 
ployed, much  timber  was  destroyed  by  being  heated  at  too  high 


48          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

temperatures  and  moreover  upkeep  charges  were  high.  It  was 
largely  due  to  such  repeated  losses  that  the  use  of  superheated 
steam  in  timber-treating  plants  fell  into  disrepute,  until  its  use 
has  now  been  practically  abandoned. 

Seasoning  in  Oil. — As  with  superheated  steam,  seasoning  in 
oil  does  not  require  a  vacuum  in  order  to  remove  the  water  from 
the  wood.  After  the  wood  is  run  into  the  treating  cylinder  and 
the  doors  closed,  creosote  oil  is  admitted  until  the  cylinder  is 
almost  full  and  all  the  wood  is  submerged.  Steam  is  then 
passed  through  coils  in  the  bottom  of  the  cylinder  and  the  oil 
raised  in  temperature  to  about  220°  F.  This  gradually  vaporizes 
the  water  in  the  wood  and  the  water  and  certain  oil  vapors  are 
passed  through  condensers  where  the  oil  can  be  separated  from 
the  water  by  allowing  it  to  settle.  The  bath  in  hot  oil  is  con- 
tinued, until,  in  the  opinion  of  the  operator,  most  of  the  water 
in  the  wood  has  been  removed.  Some  operators  continue  the 
seasoning  in  oil  until  the  amount  of  water  condensed  does  not 
exceed  one-sixth  of  a  pound  per  cubic  foot  of  wood  per  hour. 
The  cylinder  is  then  filled  with  oil  and  the  preservative  injected 
under  pressure.  At  the  present  time  this  method  of  seasoning 
is  practically  confined  to  certain  plants  on  the  Pacific  Coast, 
where  it  is  claimed  to  give  very  good  results,  especially  with 
refractory  woods  like  the  Douglas  fir.  In  addition  to  season- 
ing the  timber,  this  method  also  warms  it  for  the  reception  of 
the  preservative.  It  appears  that  this  process  may  cause  the 
wood  to  check  microscopically  and  hence  reduce  its  strength. 
This  however,  is  discussed  at  length  in  Chapter  XVIII. 

Soaking  Timber  in  Water  Preparatory  to  Seasoning  It. — If 
freshly  cut  timber  is  soaked  in  water  some  of  the  soluble  con- 
stituents which  it  contains  will  be  leached  from  the  wood.  The 
wood  cells  will,  therefore,  contain  a  larger  percentage  of  air  space 
so  that  resistance  to  absorption  of  preservative  after  the  wood  has 
been  seasoned  will  be  decreased.  In  order  to  make  this  difference 
one  of  any  appreciable  amount,  it  is  necessary  to  soak  the  timber 
for  long  periods  of  time.  In  addition  to  rendering  the  wood  more 
permeable  to  preservatives,  it  also  causes  the  wood  to  season 
with  accelerated  rapidity  after  it  is  removed  from  the  water. 
Short  periods  of  soaking  varying  from  2  weeks  to  2  months  are 
productive  of  little  or  no  beneficial  results.  This  method  has 
been  tried  on  poles  and  ties,  and  although  they  lost  weight  very 
rapidly  when  first  removed  from  the  water;  nevertheless  they 


THE  PREPARATION  OF  TIMBER  49 

failed  in  the  long  run  to  show  any  appreciable  decrease  in  weight 
over  similar  timber  not  soaked.  Furthermore,  the  amount  of 
preservative  which  they  absorbed  in  excess  of  that  absorbed  by 
timber  unsoaked  was  so  small  (about  1/2  of  1  percent)  as  to  be  of 
no  practical  value.  Unless  a  ff  eating  plant  is  so  situated  that 
it  can  afford  to  hold  timber  in  storage  for  long  periods  prior  to  its 
impregnation,  or  unless  water  soaking  can  be  conducted  (as  in 
rafting  timber)  at  a  very  small  or  no  extra  cost,  it  appears  that 
water  soaking  as  a  means  of  preparing  wood  for  treatment  is  not 
justified  by  the  results  secured. 


CHAPTER  V 
PROCESSES  USED  IN  PROTECTING  WOOD  FROM  DECAY 

Although  a  great  many  processes  have  been  and  are  practised 
in  protecting  timber  from  decay,  they  may  be  logically  divided 
into  two  rather  distinct  groups,  based  upon  the  character  of  the 
protection  given.  These  may  be  termed  the  superficial  and  the 
impregnation  processes. 

Superficial  Processes. — By  superficial  processes  is  meant  those 
processes  of  treatment  which  aim  to  protect  the  wood  by  simply 
giving  it  a  surface  protection.  Since  in  sound  timber  decay  can 
occur  only  from  external  attack,  it  is  agreed  that  if  the  surface 
of  the  wood  is  rendered  resistant  to  the  attack  of  wood-destroy- 
ing fungi,  the  entire  timber  will  remain  sound.  This  contention 
is  without  doubt  correct,  and  when  the  surface  of  a  timber  is  so 
preserved  and  the  surface  protection  is  completely  maintained, 
the  timber  may  be  made  to  last  indefinitely.  Unfortunately, 
timbers  so  treated  are  very  apt  to  have  the  protective  coating 
broken,  either  through  abrasion  or  checking.  When  this  happens 
the  untreated  interior  is  at  once  subject  to  attack,  and  the 
effect  of  the  protecting  shell  may  be  completely  destroyed.  In 
this  condition,  the  timber  may  be  very  dangerous,  as  it  gives 
the  appearance  of  being  sound  although  it  may  be  entirely  de- 
cayed in  the  interior,  and  hence  escape  detection.  The  writer 
has  seen  mine  timbers  painted  with  a  preservative  that  appeared 
on  outward  inspection  to  be  perfectly  sound,  but  when  bored 
into,  were  found  to  be  little  more  than  hollow  columns  because 
the  wood  beneath  the  surface  had  entirely  r6tted.  Furthermore, 
it  is  not  always  possible  to  detect  incipient  decay  in  wood  to  be 
treated.  In  fact,  this  is  often  impossible  without  a  microscopic 
examination,  which  is,  of  course,  impracticable  in  practice.  If 
such  wood  is  given  a  superficial  treatment,  the  incipient  decay 
in  the  interior  is  liable  to  continue  its  growth  and  thus  the 
soundness  of  the  wood  will  eventually  be  destroyed.  These 
objections  can  be  levied  against  all  superficial  processes. 

On  the  other  hand,  it  is  often  impossible  to  treat  wood  in  any 

50 


PROTECTING  WOOD  FROM  DECAY          51 

other  way  because  of  excessive  cost.  Superficial  processes 
are  of  special  usefulness  when  only  a  small  quantity  of  wood  is  to 
be  treated.  They  are  cheapr.  easily  conducted,  and  under 
ordinary  conditions,  efficient.  When  the  surface  of  the  wood 
is  not  subject  to  injury, by  abrdtion  or  checking  they  succeed  in 
greatly  prolonging  the  life  of  the  wood. 

Charring. — Charring  is  one  of  the  oldest  methods  of  pro- 
tecting timber  from  decay  that  has  been  practised.  The  wood  is 
held  over  a  fire  until  the  outer  fibers  are  charred.  This  process 
practically  surrounds  the  wood  with  a  layer  of  charcoal  which  is 
not  attacked  by  wood-destroying  fungi.  The  heat,  furthermore, 
destructively  distills  a  portion  of  the  wood  and  forms  products 
which  may  be  toxic  to  fungi.  The  depth  to  which  the  wood 
is  usually  charred  varies  from  about  1/8  to  1/2  inch.  Much  more 
effective  results  can  be  secured  by  charring  seasoned  wood  rather 
than  green  wood,  as  the  latter  will  dry  out  on  exposure  and  de- 
velop surface  checks,  which  will  break  the  continuity  of  the 
charred  surface  and  thus  expose  the  untreated  interior.  When 
air-seasoned  wood  is  properly  charred  its  life  is  increased.  The 
treatment  is  very  cheap  and  easily  applied.  It  has  a  disadvantage, 
however,  in  that  it  completely  destroys  the  strength  of  the 
outer  fibers  of  wood  and  so  weakens  the  wood.  Furthermore, 
the  beneficial  effects  secured  from  it  are  seldom  of  much 
consequence. 

Brush  Treatments. — Brush  treatments  are  more  extensively 
practised  than  any  other  of  the  superficial  processes.  (See  Plate 
VI,  Fig.  B.)  As  the  term  implies,  they  consist  in  painting  the 
preservative  on  the  surface  of  the  wood  with  a  brush.  A  large 
variety  of  preservatives  are  applied  in  this  manner,  such  as  calci- 
mine, wood  preserving  oils,  paints,  etc.  Best  results  are  secured 
by  treating  only  air-seasoned  wood,  thus  avoiding  danger  of 
subsequent  checking.  Moreover,  the  preservative  will  penetrate 
dry  wood  better  than  green.  With  certain  preservatives,  such 
as  creosote,  most  beneficial  results  are  obtained  by  heating  them 
to  180°  or  200°  F.  before  they  arepainted  onto  the  wood,  as  they 
penetrate  more  deeply  when  applied  hot.  The  penetration, 
however,  seldom  exceeds  1/4  inch  and  is  generally  much  less. 
Brush  treatments  can  be  easily  applied,  are  cheap  and  con- 
venient. In  using  them  care  should  be  taken  to  coat  all  checks, 
cracks,  and  joints  thoroughly  with  the  preservative.  The  pre- 
servative should  not  be  applied  when  the  wood  is  frozen  and 


52          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

wet.  If  an  efficient  preservative  is  used  and  properly  applied 
and  the  wood  after  treatment  is  protected  from  abrasion,  very 
satisfactory  results  can  be  expected.  Unless  these  precautions 
are  exercised,  the  treatment  may  do  no  good  whatever,  but  may 
actually  result  in  harm.  Thus,  unseasoned  telephone  poles  have 
been  examined  which  were  coated  with  ordinary  paint  and 
which  had  decayed  quicker  than  similar  poles  set  unpainted. 
In  this  case  the  poles  checked  after  they  were  treated,  allow- 
ing fungi  to  enter,  while  the  paint  formed  an  almost  imper- 
vious coating  which  kept  the  wood  moist  and  hence  in  a  very 
favorable  condition  for  rapid  decay. 

Dipping. — In  view  of  the  difficulty  of  working  the  preservative 
into  checks  and  cracks,  dipping  gives  more  effective  results  than 
brush  treating.  To  dip  wood,  however,  it  is  necessary  to  have 
some  form  of  tank  which  will  hold  the  preservative  and  which  is 
large  enough  to  allow  the  wood  to  be  submerged.  This  method 
of  treatment  is  particularly  adapted  to  small  products  such  as 
shingles  and  posts.  The  same  precautions  mentioned  under 
brush  treatments  apply  with  equal  force  to  dipping  treatments. 
On  account  of  the  greater  certainty  with  which  the  entire  surface 
of  the  wood  can  be  treated,  dipping  is  safer  to  use  than  brush 
treating  and,  in  general,  yields  better  results. 

Impregnation  Processes. — All  impregnation  processes  aim  not 
only  to  protect  the  surface  of  the  wood  from  attack  but  also  to 
force  the  preservative  deeply  into  the  wood.  Thus,  should  the 
surface  of  the  wood  become  broken,  the  fibers  beneath  the 
surface  containing  the  preservative  will  still  offer  a  strong 
resistance  to  decay.  For  this  reason  all  impregnation  processes 
are,  as  a  rule,  more  efficient  than  superficial  processes. 
The  depth  to  which  the  preservatives  will  penetrate  depends  on 
many  factors,  chief  of  which  are  the  kind  and  condition  of  the 
wood,  the  character  of  the  treatment,  and  the  kind  of  pre- 
servative used.  Nonresistant  woods  like  heart  Douglas  fir  or 
white  oak  may,  under  similar  conditions,  only  receive  a  superficial 
treatment. 

By  far  the  largest  quantity  of  wood  treated  in  the  United 
States  is  impregnated.  Impregnation  processes  are  much  more 
expensive  than  superficial  processes  and  require  more  or  less 
elaborate  apparatus.  In  connection  with  large  operations, 
however,  they  are  unquestionably  the  better  ones  to  use  and  the 
results  secured  by  them  are  the  best  obtainable.  For  purposes 


vi 


FIG.  A. — Sections  of  creosoted  piling  showing  effect  of  thin  strips  of  bark 
adhering  to  the  wood.     (Photo  through  courtesy  Southern  R.  R.) 


FIG.  B. — Brush  treating  poles.     (Forest  Service  photo.) 

(Facing  page  52.) 


PLATE  VI 


FIG.  C.— An  open  tank  plant  for  treating  the  butts  of  poles — California. 
(Forest  Service  photo.) 


FIG.  D.— Wood  preserving  plant  of  the  C.  B.  &  Q.  R.  R.,  Galesburg,  111. 
(Forest  Service  photo.) 


PROTECTING  WOOD  FROM  DECAY          53 

of  discussion,  impregnation  processes  may  be  divided  into  two 
classes,  (1)  nonpressure  processes,  or  those  using  no  " artificial" 
but  only  atmospheric  pressure*  and  (2)  pressure  processes,  or 
those  using  "artificial"  or  pressures  greater  than  atmospheric. 

Nonpressure  Processes. — These  processes  either  rely  upon 
the  absorptive  properties  of  the  wood  for  the  penetration  to  be 
secured,  or  upon  the  pressure  of  the  atmosphere  to  force  the 
preservative  into  the  wood.  Heavy  apparatus  to  withstand  pres- 
sures is  therefore  unnecessary  and  this  fact  enables  plants 
operating  on  this  basis  to  be  built  at  lower  cost  than  those  operating 
on  high  pressures.  This  is  one  of  the  chief  advantages  claimed 
for  this  method  of  treatment.  The  apparatus  may  be  an  open 
vessel  such  as  a  barrel  or  a  vat,  or  a  cylindrical  retort  of  metal 
similar  in  form  to  those  used  in  the  pressure  processes.  For  the 
treatment  of  small  quantities  of  timber,  or  when  salts  markedly 
corrosive  to  iron  are  used,  or  when  only  a  portion  of  the  timber 
is  to  be  treated,  the  rest  being  left  untreated,  these  processes 
give  very  satisfactory  results.  As  a  rule  the  penetrations  and 
absorptions  obtained  with  them  are  not  as  deep  or  as  uniform  as 
those  obtained  in  the  pressure  treatments,  although,  at  times, 
equally  as  good  results  in  this  .respect  are  secured.  The  time 
of  treatment  is  also  generally  longer  and  the  flexibility  and  con- 
trol of  the  plant  less  than  with  pressure  processes. 

Kyanizing  Process. — This  process  has  been  in  use  since  1832 
when  it  was  patented  in  England  by  John  H.  Kyan.  It  was 
employed  in  the  United  States  as  early  as  1840  and  is  claimed  to 
be  the  oldest  method  of  treating  timber  now  practised  in  our 
country.  The  process  consists  in  steeping  timber  in  a  solution 
of  bichloride  of  mercury  at  atmospheric  temperature  and  pres- 
sure. At  Portsmouth,  N.  H.,  and  Lowell,  Mass.,  the  treating 
apparatus  consists  of  solid  granite  tanks  laid  in  Portland  cement 
and  coated  on  the  inside  with  tar  applied  hot.  The  wood  to  be 
treated  is  piled  in  the  tanks  with  laths  between  each  layer  so  as 
to  allow  the  free  circulation  of  the  solution,  which  is  afterward 
pumped  into  the  tanks.  The  strength  of  the  solution  is  usually 
about  1  percent.  The  timber  is  kept  submerged  for  various 
lengths  of  time  but  a  rough  estimate  is  to  steep  it  1  day  plus  a 
day  for  each  inch  in  thickness.  Thus  2-inch  plank  is  steeped  3 
days,  6-inch  timber  7  days,  etc.  The  depth  to  which  the 
solution  penetrates  varies  largely  with  the  kind  of  wood  treated 
but  ranges  from  about  1/10  to  1/4  inch.  The  extremely  poison- 


54          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

ous  nature  of  mercuric  chloride  makes  it  imperative  to  handle  it 
with  caution.  Its  corrosive  action,  moreover,  makes  its  use 
impracticable  in  iron  or  steel  vessels  unless  specially  prepared. 
Like  all  treatments  employing  a  water-soluble  salt,  it  cannot  be 
used  to  best  advantage  if  the  timber  is  to  be  set  in  wet  situations, 
because  the  solution  will  leach  from  the  wood.  When  the 
treated  wood  is  placed  in  fairly  dry  situations,  very  good  results 
have  been  reported.  There  is  also  a  liability  of  the  salt  gradually 
crystallizing  on  the  surface  of  the  wood  where  it  may  prove 
dangerous  to  animals  should  they  lick  it.  Although  large  quanti- 
ties of  timber  have  been  treated  by  this  process,  its  use  in  this 
country  has  never  been  very  extensive.  This  is  perhaps  largely 
due  to  its  extremely  poisonous  character  and  the  comparatively 
long  time  it  takes  to  treat  the  wood.  Cases  are  on  record  where 
it  is  reported  that  spruce  posts,  Kyanized,  have  remained  service- 
able for  over  50  years,  and  hemlock  ties  for  over  13  years. 

Open-tank  Process. — Under  this  heading  we  will  consider 
several  processes  which  are  very  similar  so  far  as  the  principles 
of  treatment  are  concerned.  They  are  the  Seeley,  Giussani, 
and  nonpressure  processes.  All  of  these  processes  differ  in  prin- 
ciple from  the  Kyanizing  process,  in  that  they  aim  to  employ  the 
pressure  of  the  atmosphere  in  forcing  the  preservative  into  the 
wood.  (See  Plate  VI,  Fig.  C.)  Green  or  air  seasoned  wood  may  be 
used.  It  is  first  placed  in  a  bath  of  hot  oil  and  held  for  vari- 
ous periods,  the  object  being  to  drive  a  part  of  the  air,  sap,  and 
water  out  of  the  wood  and  thus  bring  the  wood  cells  into  a  rarified 
condition.  The  heated  timber  is  then  quickly  submerged  in  a 
cool  preservative,  whereupon  a  rapid  contraction  of  the  air  and 
water  vapor  in  the  wood  occurs,  thus  "drawing  in"  the 
preservative. 

Professor  Seeley  of  New  York  is  reported  the  first  to  make 
use  of  this  principle  on  a  commercial  scale,  he  having  secured 
patents  on  it  in  1868.  Seeley  used  creosote  oil  and  claimed  to 
treat  either  green  or  seasoned  wood.  (See  Chapter  I  for 
further  discussion.) 

About  1898  Tomasco  Giussani  invented  a  similar  process 
in  Italy  which  he  claimed  made  possible  the  impregnation  of 
timber  with  dead  oil  of  tar  alone,  with  salt  solutions  alone, 
or  combinations  of  the  two.  Open  tanks  are  used  and  the  process 
is  a  continuous  one.  The  timber  either  green  or  seasoned  is 
carried  by  a  conveyor  to  the  first  tank,  which  contains  heavy 


PROTECTING  WOOD  FROM  DECAY          55 

creosote  oil  heated  to  about  280°  F.,  where  it  is  kept  submerged 
until  ebullition  ceases  (a  period  of  from  1  to  4  hours). 
It  is  then  conveyed  mechanically  to  another  open  tank  con- 
taining cold  creosote  oil  or  zinc  chloride  or  any  other  preserv- 
ing salt  until  the  desired  absorption  has  been  obtained  (a  period 
of  from  2  to  3  hours),  after  which  the  treatment  is  finished 
and  the  timber  is  mechanically  removed  from  the  treating  vats. 
This  process  was  demonstrated  at  the  St.  Louis  Exposition  in 
1904  where  it  was  awarded  a  Grand  Prize.  Two  plants  operating 
on  this  process  are  located  in  Rome  and  Milan,  Italy,  but  so  far 
as  the  author  knows,  it  is  not  practised  in  the  United  States.  By 
this  method  of  treatment  deep  penetrations  of  the  preservative 
are  possible,  which,  in  certain  timbers  like  loblolly  pine  ties, 
may  extend  to  the  center.  In  plants  operating  on  this  basis  the 
diffusion  and  absorption  of  the  preservative  cannot  be  as  practi- 
cally controlled  as  in  pressure  plants,  but  for  a  low  initial  cost  of 
installation  they  are  efficient. 

In  1904  the  U.  S.  Bureau  of  Forestry  (now  the  Forest  Service) 
conducted  an  extensive  series  of  tests  with  what  is  called  the 
" open-tank"  process  at  the  St.  Louis  Exposition.1  This  method 
of  treatment  has  since  been  extensively  tested  by  the  Forest 
Service  with  a  view  to  perfecting  it  and  evolving  a  process  which 
could  be  efficiently  used  by  the  small  consumer.  It  secured  its 
name  from  the  character  of  the  apparatus  in  which  the  treatments 
are  made,  these  being  open  tanks  of  any  convenient  size  and  shape. 
Later  experiments  lead  to  the  use  of  closed  tanks  or  cylinders  for 
certain  treatments  and  the  term  "  nonpressure "  was  employed 
to  designate  the  process  carried  on  in  them.  In  principle,  there- 
fore, it  differs  in  nowise  from  any  of  the  " open-tank"  processes. 
In  open-tank  treatments  the  Forest  Service  recommends  only  the 
use  of  air-seasoned  wood.  This  is  subjected  to  a  bath  in  hot 
creosote,  but  temperatures  above  250°  F.  are  not  recommended 
as  they  are  liable  to  injure  the  wood.  The  wood  is  then  either 
allowed  to  remain  in  the  hot  oil,  which  is  gradually  cooled,  or 
else  changed  to  a  tank  containing  cool  oil,  or  cool  oil  is  pumped 
into  the  tank  containing  the  timber  after  the  hot  oil  has  been  re- 
moved. The  process  is  adapted  to  the  use  of  various  preserva- 
tives such  as  creosote,  crude  oil,  zinc  chloride,  etc.  Very  good 
penetrations  are  secured,  in  fact  these  compare  favorably  with 

Circular  101,  "The  Open-tank  Treatment  of  Timber,"  by  Carl  G. 
Crawford,  Washington,  D.  C. 


56          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

those  secured  in  pressure  processes.  This  process  is  admirably 
adapted  to  the  treatment  of  poles  and  posts  where  only  a  portion 
of  the  stick  is  to  be  treated.  Plants  operating  on  this  basis  are 
comparatively  cheap.  It  is  possible  to  control  fairly  accurately 
the  character  of  the  penetration  and  absorption,  especially  in 
woods  which  lend  themselves  readily  to  treatment,  like  sap  pine. 
For  example,  if  a  deep  penetration  is  desired  with  a  comparatively 
small  absorption  of  oil,  the  timber  should  be  left  in  cool  oil  for  only 
a  short  period  after  it  is  removed  from  the  hot  bath.  Another 
way  is  to  re-treat  the  wood  after  it  has  been  treated  in  cool  oil. 
This  tends  to  drive  out  a  part  of  the  oil  in  the  wood  provided  it 
is  removed  from  this  second  hot  bath  while  it  is  still  hot.  If 
a  heavy  absorption  is  desired,  the  wood  should  be  heated 
thoroughly  and  then  submerged  in  cool  oil  until  the  temperature 
of  the  wood  has  reached  that  of  the  oil. 

If  it  is  desired  to  impregnate  the  wood  with  a  water-soluble 
salt  like  zinc  chloride,  this  may  be  done  by  boiling  the  wood  in 
the  solution  (which,  however,  is  very  apt  to  weaken  it)  and  then 
allowing  it  to  cool,  or  by  boiling  the  wood  in  oil  for  a  short 
time  and  then  submerging  it  in  a  solution  of  the  salt.  In  this 
way  a  deep  penetration  of  the  salt  can,  at  times,  be  secured, 
while  the  outer  portion  of  the  wood  will  have  an  added  protection 
due  to  the  small  amount  of  oil  which  it  contains. 

The  length  of  time  required  to  treat  wood  by  the  open  tank 
method  is  very  variable,  but  a  hot  bath  of  1  to  3  hours 
followed  by  a  cool  bath  of  the  same  or  a  longer  period  is  usually 
sufficient.  A  number  of  open-tank  plants  are  now  in  operation 
in  the  United  States,  chiefly  by  farmers  and  mine  and  telephone 
companies. 

Pressure  Processes. — All  processes  so  classed  rely  upon  the 
use  of  pressures  above  atmospheric  in  order  to  force  the  pre- 
servative into  the  wood.  (See  Plate  VI,  Fig.  D.)  In  general,  best 
results  are  secured  by  such  treatment,  although  it  is  by  no 
means  possible  to  satisfactorily  penetrate  all  woods  even  with 
the  use  of  high  pressures. 

Bethell  (Full-cell  Creosote}  Process. — This  process  is  named 
after  John  Bethell  who  took  out  patents  in  England  in  1838. 
It  is  commonly  referred  to  in  our  country  as  the  "  full-cell 
process. "  'Either  green  or  seasoned  timber  can  be  treated  by 
this  process,  creosote  oil  (dead  oil  of  coal-tar)  being  the  pre- 
servative used.  The  timber  to  be  treated  is  loaded  upon  steel 


PROTECTING  WOOD  FROM  DECAY          57 

cars  or  "buggies,"  which  are  run  into  horizontal  steel  cylinders 
usually  7  feet  in  diameter  by  132  feet  long.  Their  length,  how- 
ever, varies  from  about  50  Jo"- 180  feet  and  diameter  from  6  to  9 
feet.  If  the  timber  is  green,  ij^is  subjected  to  a  bath  of  live  steam 
for  several  hours,  after  which  a  vacuum  is  drawn  by  means  of 
pumps.  This  also  is  held  for  one  or  more  hours  according  to  the 
judgment  of  the  operator.  If  the  timber  is  air  seasoned,  the 
steam  bath  is  generally  omitted.  Creosote  oil  is  then  run  or 
pumped  into  the  cylinder  and  a  pressure  of  100  to  180  pounds 
applied  until  the  gauges  show  the  desired  amount  of  oil  has  been 
forced  into  the  wood.  The  excess  oil  is  then  drained  from  the 
treating  cylinder  and  the  timber  is  allowed  to  drip  for  a  short 
period,  after  which  the  process  is  ended  and  the  charge  is  removed. 
Many  treating  engineers  draw  a  vacuum  in  the  cylinder  after 
the  excess  oil  has  drained  from  it,  as  this  tends  to  hasten  the 
drip  and  dry  the  timber.  The  Bethell  or  full-cell  process  is 
considered  the  standard  process  of  treating  timber  with  creosote, 
and  the  most  effective  results  in  prolonging  the  life  of  wood 
have  been  secured  by  it.  On  account  of  the  relatively  large 
amount  of  oil  which  the  ties  absorb,  the  process  is,  however, 
the  most  expensive  and  for  this  reason  several  modifications 
have  been  made. 

Boiling  Process.  — This  process  was  patented  in  the  United 
States  by  W.  G.  Curtis  and  John  D.  Isaacs  and  the  patent 
number  was  reissued  November  1,  1895.  It  is  used  almost 
exclusively  on  the  Pacific  Coast,  largely  for  the  treatment  of 
Douglas  fir.  Either  green  or  seasoned  wood  can  be  treated, 
although  the  former  is  at  present  in  more  extended  use.  The 
wood  is  run  into  cylinders  as  in  the  Bethell  process  and  im- 
mersed in  creosote  oil  heated  at  the  start  to  about  160°  F.  A 
space  of  about  10  inches  is  left  clear  from  the  top  of  the  oil  to 
the  top  of  the  treating  cylinder.  The  oil  is  heated  by  means  or 
steam  coils  in  the  bottom  of  the  cylinder  and  the  temperature 
gradually  raised  to  about  225°  F.  The  vapors  of  oil  and  wates 
passing  over  are  condensed  in  a  surface  condenser.  The  oil  if 
kept  at  a  temperature  of  about  225°  F.  until  the  rate  of  evapora- 
tion does  not  exceed  about  1/6  of  a  pound  of  water  per  cubic 
foot  of  wood  in  the  charge  per  hour;  this  being  to  drive  the  sap 
and  water  out  of  the  wood.  The  treating  cylinder  is  then 
filled  with  creosote  oil  at  a  pressure  of  5  pounds  per  square 
inch,  the  temperature  falling  to  about  200°  F.  The  pressure 


58          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

pump  is  then  started  and  held  at  about  150  pounds  per  square 
inch  until  the  gauges  show  the  desired  amount  of  oil  has  been 
forced  into  the  timber.  After  injection,  the  pressure  is  slowly 
released  through  an  overflow  pipe,  the  excess  oil  drawn  from  the 
cylinders,  and  the  charge  removed.  In  treating  dry  sawn 
timber,  temperatures  above  214°  F.  and  pressures  over  120 
pounds  per  square  inch  are  not  recommended  by  the  advocates 
of  this  process.  It  can  thus  be  seen  that  the  boiling  process 
resembles  the  Bethell  process  except  for  the  preliminary  treat- 
ment which  the  timber  is  given. 

The  Buehler  Process. — Walter  Buehler  secured  two  patents 
in  the  United  States  on  September  22,  1908  (Nos.  899237  and 
899480)  on  the  process  which  bears  his  name.  Either  green 
or  seasoned  timber  can  be  treated,  the  preservative  being 
creosote  oil.  The  process  is  not  at  present  in  extended  use. 
Green  or  water-soaked  timber  is  treated  as  follows.  It  is  run 
into  the  treating  cylinder  as  in  the  Bethell  process  and  im- 
mersed in  creosote  heated  to  a  temperature  of  not  less  than 
140°  F.,  the  cylinder  being  completely  filled  with  oil.  The 
temperature  of  the  oil  in  the  cylinder  is  kept  gradually  rising 
as  fast  as  the  condensation  will  permit  until  it  reaches  between 
220°  and  260°  F.  It  is  then  held  to  maintain  a  regular  and 
constant  temperature  within  the  cylinder.  During  this  season- 
ing period  the  gauge  on  the  cylinder  should  show  a  pressure  of 
not  more  than  5  pounds.  The  maximum  temperature  is 
maintained  until  the  condensation  in  the  hot  well  shows  the 
interior  of  the  wood  "to  be  sufficiently  dry,"  when  the  steam 
in  the  coils  is  released  and  the  cylinder  filled  with  creosote,  the 
temperature  being  lowered  to  about  200°  F.,  when  the  pressure 
pump  is  started  and  the  oil  is  forced  into  the  wood  until  the 
desired  amount  has  been  absorbed.  The  cylinder  is  then 
drained  of  excess  oil  and  an  air  pressure  of  15  to  25  pounds  per 
square  inch  is  applied  and  held  to  penetrate  all  of  the  wood. 
This  completes  the  process. 

For  air-seasoned  timber,  a  vacuum  of  at  least  20  inches  is 
drawn  after  the  wood  is  placed  in  the  cylinder,  and  held  for  at 
least  20  minutes.  Creosote  is  then  admitted  and  pressure  ap- 
plied with  the  force  pump  until  the  proper  amount  of  oil  has 
been  injected.  The  excess  oil  is  then  drained  from  the  cylinder 
and  an  air  pressure  of  15  to  25  pounds  is  maintained  until  the 


PROTECTING  WOOD  FROM  DECAY          59 

maximum  pressure  remains  constant  for  at  least  15  minutes,  after 
which  the  treated  timber  is  removed  from  the  cylinder. 

Tests  made  by  the  author  showed  that  air  pressures  applied 
to  wood  freshly  impregnate&  with  creosote  forced  much  of  the 
creosote  out  of  the  wood  after  these  pressures  were  released  and 
greatly  prolonged  the  time  it  took  the  timber  to  drip. 

The  A.  C.  W.  Process. — In  the  A.  C.  W.  process,  so  called 
after  the  American  Creosote  Works  in  Louisiana  in  which  it  is 
practised,  after  the  timber  has  been  subjected  to  a  preliminary 
seasoning  of  live  steam,  and  after  a  vacuum  has  been  drawn,  air 
is  forced  into  the  cylinder  until  a  pressure  of  about  15  pounds  is 
obtained.  Creosote  is  then  admitted,  the  air  pressure  being 
still  maintained  to  prevent  excessive  or  unequal  absorption  of 
the  oil  while  the  cylinder  is  being  filled.  The  surplus  air  is  al- 
lowed to  escape  through  a  pop  valve  at  the  top  of  the  cylinder. 
When  the  cylinder  is  full  of  oil  a  pressure  of  100  pounds  or  more  is 
applied  with  a  pump  until  the  proper  amount  of  the  creosote  has 
been  forced  into  the  timber.  The  oil  is  then  run  from  the  treating 
cylinder  and  an  air  pressure  of  60  to  80  pounds  applied.  This 
is  introduced  to  drive  the  oil  into  the  wood  to  a  greater  depth 
and  to  secure  greater  uniformity  of  treatment. 

The  process  is  not  in  general  use  and  is  practically  confined  to 
the  plant  operated  by  the  American  Creosote  Works. 

The  Lowry  Process. — This  process  is  covered  in  the  United 
States  by  Patent  No.  831450,  issued  to  C.  B.  Lowry  under  date  of 
September  18,  1906. 

Air-seasoned  timber  is  loaded  on  tram  cars  and  placed  within 
the  treating  cylinder.  The  cylinder  is  then  filled  from  the 
charging  tank  with  creosote  oil  at  a  temperature  not  to  ex- 
ceed 200°  F.  The  main  line  is  then  closed  and  oil  from  the 
charging  tank  is  forced  by  pressure  pumps  into  the  retort 
until  the  timber  has  taken  oil  to  the  point  of  refusal,  or  a 
predetermined  amount.  The  pressure  and  temperature  within 
the  retort  are  controlled  so  as  to  give  a  maximum  penetration 
of  the  oil.  The  pressure  is  then  released  and  the  free  oil  in 
the  retort  is  drained  off.  A  vacuum  of  sufficient  degree  and 
duration  is  then  drawn  in  the  retort  to  recover  that  portion 
of  the  free  oil  in  the  timber  above  the  specified  amount.  The 
recovered  oil  is  then  drained  off  from  the  retort  and  the  charge 
is  withdrawn.  The  Lowry  process  may  be  termed  an  "  empty- 
cell"  process  in  that  it  aims  to  secure  a  deep  penetration  of 


60          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

creosote  without  consuming  as  much  of  it  as  the  Bethell  or  full- 
cell  process.  At  the  present  time  the  process  is  in  very  extended 
use  in  the  United  States,  particularly  in  treating  cross-ties,  eleven 
plants  now  operating  under  its  patent. 

Rueping  Process. — This  is  also  termed  an  "  empty-cell " 
process  in  that  the  object  sought  is  a  deep  penetration  of  creosote 
with  a  comparatively  small  consumption  of  the  oil.  It  was 
patented  in  the  United  States  on  September  23,  1902,  the  issue 
being  to  Messrs.  Halsberg  &  Co.,  M.  B.  H.,  of  Germany.  The 
timber  to  be  treated  should  preferably  be  air-seasoned.  Green 
or  partially  seasoned  wood  is  subjected  to  a  steam  and  vacuum 
bath  similar  to  that  given  in  the  Bethell  process  before  the  treat- 
ment is  begun.  After  the  timber  has  been  placed  in  the  treating 
cylinder,  compressed  air  is  admitted  frequently  from  an  overhead 
tank  and  held  until  the  wood  is  filled  with  compressed  air.  Creo- 
sote is  then  admitted  under  a  slightly  higher  pressure,  the  air  in 
the  cylinder  gradually  escaping.  When  the  cylinder  is  filled 
with  creosote  the  pressure  on  the  oil  is  raised  to  about  150  or 
more  pounds  and  held  until  no  more  oil  can  be  forced  into  the 
wood.  The  cylinder  is  than  drained  of  oil  and  a  final  vacuum 
drawn  to  increase  the  expansive  force  of  the  air  in  the  timber  and 
to  dry  the  wood  as  quickly  as  possible.  The  length  of  time  the 
compressed  air  is  held,  the  pressure  of  the  compressed  air,  the 
length  and  pressure  of  the  oil  period,  and  the  length  of  the  final 
vacuum  all  vary  with  the  kind  of  timber  under  treatment. 
When  they  are  properly  adjusted,  penetrations  as  deep  as  those 
secured  in  the  Bethell  process  are  obtained,  in  some  cases  with 
one-half  or  less  the  consumption  of  oil.  Rueping-treated  timber 
has  a  tendency  to  drip  much  longer  than  timber  treated  without 
the  use  of  compressed  air,  and  the  rate  of  evaporation  of  the 
creosote  from  it  is  also  likely  to  be  greater.  The  process  is  now 
in  extended  use  in  both  the  United  States  and  Europe. 

Burnett  Process. — William  Burnett  patented  this  method  of 
treatment  in  England  in  1838  and  it  has  been  in  constant  use 
since.  It  is  commonly  referrred  to  as  the  standard  process 
using  a  water-soluble  salt,  chloride  of  zinc.  The  method  of 
treatment  is  exactly  analogous  to  the  Bethell  process,  the  only 
essential  difference  being  in  the  character  of  the  preservative. 
As  a  general  rule,  water  solutions  can  be  forced  into  wood  deeper 
than  oils,  so  that  under  any  given  set  of  conditions  slightly  better 
penetrations  are  secured  from  the  use  of  zinc  chloride  than  from 


PROTECTING  WOOD  FROM  DECAY          61 

creosote.  The  Burnett  treatment  is  in  extensive  use  in  the 
United  Stated  and  Europe,  where  it  has  given  excellent  results 
in  prolonging  the  life  of  timber  not  set  in  very  wet  conditions. 
On  account  of  the  soluble  ^nature  of  the  salt,  several  methods 
have  been  employed  4o  retara  its  leaching  action,  some  of  which 
are  now  extensively  practised. 

Rutgers  Process. — The  objections  of  the  comparatively  high 
cost  of  creosote  and  the  leachability  of  zinc  chloride  are  both 
partially  overcome  by  the  Rutgers  process,  invented  by  Julius 
Rutgers  in  Germany  about  1874.  Rutgers  handles  the  timber  to 
be  treated  in  much  the  same  way  as  is  done  in  the  Bethell  pro- 
cess, but  employs  a  mixture  of  zinc  chloride  and  creosote  as  his 
preservative.  The  zinc  chloride  is  generally  in  a  3  to  5  percent 
solution  and  comprises  about  80  percent  of  the  mixture.  To  this 
a  comparatively  low-gravity  creosote  free  from  naphthalene  is 
added  by  means  of  a  jet  of  steam  or  air  or  other  suitable  mixing 
device.  The  timber  thus  treated  contains  both  creosote  and  zinc 
chloride  injected  simultaneously.  While  the  process  is  not 
practised  in  the  United  States,  it  has  found  extensive  use  in 
Germany,  where  it  is  reported  to  give  marked  satisfaction, 
particularly  in  the  treatment  of  cross-ties. 

Card  Process. — The  principle  of  injecting  timber  simultaneously 
with  zinc  chloride  and  creosote  was  adopted  by  J.  B.  Card,  to 
whom  a  patent  was  granted  in  the  United  States  on  March  20, 
1906.  Card's  process  differs  essentially  from  that  of  Rutgers  in 
the  manner  of  keeping  the  solution  mixed.  He  uses  about  80  per- 
cent of  zinc  solution  to  20  percent  of  creosote,  the  strength  of 
the  zinc  being  regulated  so  that  approximately  1/2  pound  of  the 
dry  salt  will  be  injected  with  each  cubic  foot  of  wood  treated. 
This  solution  is  first  mixed  in  the  measuring  tank  by  forcing  air 
through  perforated  pipes  placed  on  the  bottom.  When  the 
solution  is  run  into  the  treating  cylinder,  the  agitation  is  continued 
by  means  of  a  centrifugal  pump  which  draws  it  from  the  top  of  the 
retort  and  returns  it  through  a  perforated  pipe  running  length- 
wise in  the  bottom  of  the  cylinder.  The  steps  in  the  Card  proc- 
ess are  analogous  to  those  in  the  Bethell  process.  Air-seasoned 
timber  is  advocated.  After  this  is  run  into  the  cylinder  a  vacuum 
of  22  to  26  inches  is  drawn  for  about  1  hour.  The  preservative 
mixture  is  then  admitted  at  a  temperature  of  about  180°  F.  and  a 
pressure  of  about  125  pounds  per  square  inch  applied  to  it  by 
means  of  force  pumps  for  3  to  5  hours,  or  until  the  desired 


62          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

absorptions  have  been  secured.  During  this  period,  the  centrif- 
ugal pump  is  kept  running  in  the  manner  described  above,  to 
agitate  the  solution  in  the  cylinder.  The  cylinder  is  then  drained 
of  excess  preservative  and  a  final  vacuum  drawn  to  assist  in  dry- 
ing the  timber,  after  which  the  charge  is  removed.  Difficulty 
may  be  experienced  in  keeping  the  solution  uniform  during  treat- 
ment, unless  the  proper  conditions  are  maintained.  Good 
penetrations  of  both  creosote  and  zinc  chloride  are  secured  in  this 
process,  which  is  now  extensively  used  in  the  United  States, 
particularly  for  the  treatment  of  cross-ties. 

Wellhouse  Process. — Experience  with  the  Wellhouse  or  zinc-tan- 
nin process  began  about  1881,  when  some  ties  were  treated  in  St. 
Louis,  Mo.  In  the  early  80's  and  90's  this  method  of  treatment 
was  extensively  used  in  the  United  States  but  at  the  present  time 
the  amount  of  timber  treated  by  it  is  comparatively  small.  The 
chief  objections  to  its  use  were  apparently  the  many  manipula- 
tions required  and  the  difficulty  of  satisfactorily  operating  them. 

The  timb'er  to  be  treated  is  handled  much  the  same  as  in 
the  Burnett  process  except  for  the  manipulations  of  forcing  the 
preservative  into  the  timber.  After  the  timber  has  been  placed 
in  the  treating  cylinder  and  seasoned,  as  in  Burnettizing,  a  so- 
lution of  zinc  chloride  and  glue  in  the  proportions  of  1  1/2  to  3 
percent  of  the  former  to  one-half  of  1  percent  of  the  latter 
is  forced  into  the  wood  by  means  of  pressure  pumps  under  a 
pressure  of  about  125  pounds  per  square  inch  and  held  for  3  to  6 
hours.  The  excess  preservative  is  then  drained  from  the  cylinder 
and  a  water  solution  of  one-half  of  1  percent  tannin  is  introduced 
and  forced  into  the  timber  at  125  pounds  pressure  for  about  2 
hours,  after  which  the  excess  tannin  solution  is  drained  from 
the  cylinder  and  the  charge  removed.  The  tannin  combines  with 
the  glue  and  forms  a  " leathery  substance"  which  tends  to  plug  up 
the  pores  of  the  wood  and  retard  the  zinc  chloride  from  leaching 
out.  The  process  was  later  modified  by  injecting  the  glue  sepa- 
rately, it  being  found  that  it  retarded  the  entrance  of  the  zinc 
solution.  The  temperature  of  the  treating  solution  as  well  as 
the  strength  of  the  zinc  chloride  used  was  also  raised. 

While  the  mixture  of  glue  and  tannin  does  tend  to  plug  the 
wood  cells,  nevertheless,  the  extent  to  which  they  do  this  has 
been  exaggerated.  The  zinc-chloride  solution  not  only  resists 
the  entrance  of  the  glue  and  tannin  in  subsequent  injection,  but 
the  air  confined  in  the  wood  tends  to  push  the  plug  out  of  the 


PROTECTING  WOOD  FROM  DECAY          63 

cells  due  to  its  expansive  force.  Microscopic  examinations  of 
Well  house-treated  wood  have  shown  that  the  "plug"  is  only  a 
surface  coating  and  seldom  actually  extends  into  the  timber. 
While  very  good  results  have  been  secured  from  this  method  of 
treatment,  it  is  believed  that  letter  results  could  have  been  ob- 
tained if  a  strong  preliminary  vacuum  had  been  drawn  and  held 
while  the  zinc  solution  was  entering  the  cylinder.  The  Well- 
house  process  is  comparatively  cheap,  costing  about  18  cents  per 
tie,  and  has  succeeded  in  more  than  doubling  the  life  of  ties  which 
like  hemlock,  red  oak,  and  gum  decay  very  rapidly. 

Allardyce  Process. — So  called  after  R.  L.  Allardyce,  who  sug- 
gested its  use.  The  timber  to  be  treated  is  handled  much  as  in  the 
Wellhouse  process  except  that  creosote  instead  of  glue  and  tannin 
is  used.  A  4  percent  zinc-chloride  solution  is  forced  into  the 
wood  at  a  pressure  of  about  130  pounds  per  square  inch,  after 
which  the  cylinder  is  drained  and  refilled  with  creosote,  this  be- 
ing injected  under  a  pressure  of  about  180  pounds  per  square  inch 
so  as  to  form  a  continuous  outer  layer  around  the  zinc-treated 
timber.  As  might  be  expected,  the  penetration  of  the  creosote  is 
slight.  If,  however,  the  timber  is  removed  from  the  cylinder  after 
its  injection  with  zinc  chloride  and  allowed  to  air  season,  and  then 
re-treated  with  creosote,  better  results  are  obtained.  The  delay 
thus  occasioned  and  the  increased  cost  of  handling  then  become 
serious  objections.  The  Allardyce  process  is  not  in  extensive 
use  at  this  time. 

The  author  treated  a  number  of  red  oak  and  maple  ties  by 
reversing  the  Allardyce  method.  These  were  first  impregnated 
with  2  to  3  pounds  of  creosote  per  cubic  foot,  after  which 
the  cylinder  was  drained  and  refilled  with  a  3  percent  zinc- 
chloride  solution  forced  into  the  wood  until  1/2  pound  of  the 
dry  salt  was  injected.  The  cylinder  was  drained  and  the 
charge  removed.  The  results  secured  were  very  similar  to  those 
obtained  in  the  Card  process,  much  of  the  creosote  being  carried 
further  into  the  wood.  By  this  manipulation,  delay  in  treating 
and  increased  cost  of  handling  are  avoided,  but  unless  extreme 
care  is  exercised  the  zinc-chloride  solution  will  soon  become 
contaminated  with  the  creosote,  so  that  the  amount  of  each  con- 
sumed will  become  a  matter  of  speculation. 


CHAPTER  VI 

PRESERVATIVES  USED  IN  PROTECTING  WOOD  FROM 

DECAY 

/ 

Properties  of  Efficient  Preservatives. — Hundreds  of  chemicals 
and  compounds  have  been  advocated  and  tested  to  preserve 
wood  from  decay,  but  only  a  few  of  them  possess  sufficient 
merit  to  justify  their  use  for  this  purpose.  As  was  shown  in 
Chapter  II,  decay  in  timber  is  caused  by  fungi  and  bacteria. 
To  preserve  wood  from  decay  it  is  therefore  absolutely  essential 
to  protect  it  from  the  attacks  of  these  organisms.  In  brief,  all 
fungi  and  bacteria  which  decay  wood  require  certain  amounts 
of  heat,  air,  moisture,  and  food  in  order  to  live.  If  one  or  mose 
of  these  essentials  can  be  eliminated,  these  organisms  cannot 
live  and  hence  wood  will  remain  sound  indefinitely.  The  basic 
problem,  therefore,  in  any  efficient  preservative  process  is  to  ac- 
complish this.  Obviously  a  control  of  heat  and  air  around  struc- 
tural timber  set  subject  to  decay  is  exceedingly  difficult  and 
generally  impracticable.  Hence  a  control  of  the  moisture  in 
the  wood  and  the  food  of  the  fungus  (which  is  the  wood  sub- 
stance) are  the  two  most  practical  lines  of  preventing  attack. 
Wood  kept  constantly  under  water  is  too  wet  to  permit  the  fungi 
to  grow  and  hence  will  remain  sound  ad  infinitum.  Conversely, 
wood  kept  constantly  air  dry  or  drier  contains  too  little  moisture 
for  fungous  growth  and  will  never  decay — to  wit,  the  durability 
of  furniture  in  dwellings,  etc.  All  successful  wood  preservatives, 
therefore,  either  keep  the  wood  comparatively  dry  or  else  poison 
the  wood  so  that  the  organisms  attacking  it  are  killed. 

The  amount  of  moisture  in  wood  necessary  for  the  growth  of 
wood-destroying  fungi  is  not  definitely  known.  It  is  the  author's 
opinion  that  in  general  it  must  be  not  less  than  20  percent. 
Certain  fungi  which  have  the  ability  of  making  or  transporting 
moisture  may  be  able  to  attack  wood  containing  a  smaller 
moisture  content  than  this.  It  is  well  known  that  posts  set  in 
the  ground  decay  in  or  near  the  ground  and  rarely  in  the  top. 
To  secure  some  data  on  the  distribution  of  moisture  in  posts, 
the  author  placed  several  cedar  posts  in  the  ground  and  took 

64 


PRESERVATIVES  USED  IN  PROTECTING  WOOD  65 

moisture  borings  2  inches  deep  2  feet  below  ground  level, 
at  ground  level,  and  3  feet  above  ground  level,  at  various 
periods  extending  over  a  year;-  That  portion  of  the  posts  buried 
in  the  ground  contained  in  general  about  30  percent  moisture, 
that  near  the  ground  line  about  32  percent,  and  that  near  the 
top  less  than  17  percent.  If,  then,  wood  can  be  impregnated 
or  coated  with  a  substance  that  will  ke6p  it  comparatively  dry, 
the  fungi  and  bacteria  will  be  unable  to  develop  and  the  wood 
will  remain  sound.  This  is  the  basic  principle  involved  in  the 
use  of  nontoxic  oils,  like  petroleum. 

In  general,  most  effective  results  in  prolonging  the  life  of  timber 
from  decay  are  obtained  by  using  some  chemical  which  is  toxic 
and  which  thus  poisons  the  food  of  the  fungus.  Toxic  preserva- 
tives differ  considerably  in  their  effectiveness  against  fungi. 
Considerable  work  has  been  done  by  a  number  of  investigators 
to  determine  the  smallest  amount  of  preservative  necessary  to 
inhibit  fungous  growth.  This  is  called  the  "toxic  limit."  One 
of  the  most  satisfactory  methods  of v  doing  this  is  by  means  of 
cultures  in  glass  dishes  by  what  is  known  as  the  "petri-dish 
method."  It  consists,  in  brief,  in  pouring  into  the  sterilized 
petri-dishes  a  solution  of  agar-agar  of  the  following  approximate 
composition:  Juice  from  1  pound  of  beef,  25  grams  of  Loff- 
lund's  malt  extract,  20  grams  of  agar-agar,  and  1000  c.c.  of  dis- 
tilled water.  Upon  this  medium  is  placed  a  small  mat  of  fungus 
mycelium.  The  dish  thus  inoculated  is  placed  in  a  constant 
temperature  oven  for  about  6  weeks.  Various  amounts  of  the 
preservative  to  be  tested  are  weighed  on  a  chemical  balance  and 
mixed  into  the  culture  medium.  The  fungus  will  grow  readily 
on  low  concentrations  but  a  concentration  is  finally  reached 
above  which  no  growth  occurs.  The  smallest  concentration 
which  inhibits  growth  is  called  the  "toxic  limit"  or  "toxicity" 
of  the  preservative.  A  number  of  preservatives  have  been 
tested  in  this  manner  by  C.  J.  Humphrey  at  the  U.  S.  Forest 
Products  Laboratory,  the  results  being  given  in  Table  4 
The  greater  the  toxicity  of  a  preservative,  the  greater  is  its 
ability  to  kill  fungi  and  keep  wood  sound.  It  frequently  happens, 
however,  that  those  preservatives  which  are  most  toxic  are  not  the 
ones  which  give  best  satisfaction  in  prolonging  the  life  of  wood, 
because  they  may  have  certain  inherent  characteristics  which 
vitiate  or  preclude  their  use.  Chief  among  these  are  their 
permanency,  and  corrosion  of  iron. 

5 


66 


THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


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PRESERVATIVES  USED  IN  PROTECTING  WOOD 


67 


Practically  all  inorganic  preservatives  are  soluble  in  water, 
and  will,  if  exposed  to  ordinary  atmospheric  conditions,  leach 
out  of  wood.  If  they  should  do  this  at  a  rapid  rate,  the  wood 
will  soon  he  left  unprotected  so  that  the  fungi  can  attack  it. 
In  order  to  be  effective,  therefore,  such  preservatives  must 
remain  in  the  wood  for  long  periods. 

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many  of  them  volatilize  when  exposed  to  the  atmosphere,  so 


10 


20 


30  40  50  60 

Time  of  Seasoning  after  Treatment -Days 


80 


FIG.  5. — Comparative  rates  at  which  fractions  of  coal-tar  creosote  evaporate 
from  wood.     (Cir.  188,  U.  S.  Forest  Service.) 


that  the  amount  remaining  in  the  treated  timber  may  eventually 
become  so  small  as  to  be  ineffective  in  further  protecting  the 
wood  from  decay.  This  is  particularly  true  of  the  lighter 
fractions  of  coal-tar  creosote,  as  is  shown  in  Fig.  5,  which 
represents  the  rate  at  which  various  fractions  of  coal-tar  creosote 
and  creosote  evaporated  from  sap  loblolly  pine  sticks  6  inches  in 
diameter  and  24  inches  long  impregnated  with  about  18  pounds 


68 


THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


each  of  oil  and  later  exposed  to  the  atmosphere. l  in  this  figure  the 
temperature  represents  the  limits  between  which  the  distillates 
were  obtained  from  the  creosote.  The  permanency  of  the 
higher  boiling  fractions  "is  well  shown.  Other  tests2  made  on 
timbers  subjected  to  service  for  20  or  more  years  also  show  that 
the  higher  boiling  constituents  are  the  most  permanent. 

TABLE  5. — CORROSIVE  ACTION  OF  THE  PRESERVATIVE3 


Preservatives    designated    by    manufac- 
turer as 

Loss  in  weight  (grams)  of  flange  steel  after 
immersion  in  preservative  at  98°  C.  for 

3  weeks 

4  weeks 

Coal-tar  creosote  

0.0064 
0.0000 

0.0389 
0.0063 
0.0313 
0.0005 
0.0807 
8.2629 
5.0989 
1.2938 
0.0243 
0.2222 
0.0096 
0.0012 
1.4636 
0.6050 
1.3809 
3.1660 
0.1256 
0.0139 

Coal-tar  creosote  Frac.  1  

0.0008 
0.0401 
0.0467 
0.0296 
0.0015 
0.0951 
11.2350 

Coal-tar  creosote  Frac.  2  
Coal-tar  creosote  Frac  3 

Coal-tar  creosote  Frac.  4  
Coal-tar  creosote  Frac.  5  
Averarius  carbolineum  
Hardwood  tar 

Wood  creosote  (Douglas  fir)  
Spirittine  

1.5029 

1.07  oil  

Timberasphalt  

Copperized  oil 

Fuel  oil  

0.0062 

Zinc  chloride 

Zinc  sulphate  (a)  
Zinc  sulphate  (6)  by-product.  .    .  . 
B.  M.  preservative  

4.1746 
0.1588 
0.0181 

Sodium  fluoride 

Cresol  calcium  

(a)  Equivalent  to  2. 1  percent 
(6)  Equivalent  to  6. 2  percent 


zinc-chloride  solution, 
zinc-chloride  solution. 


As  nearly  all  wood  preserving  plants  are  built  of  steel  cylinders, 
any  preservative  which  attacks  steel  cannot,  of  course,  be  used  in 
them.  This  excludes  such  preservatives  as  mercuric  chloride, 
copper  sulphate,  etc.,  from  standard  practice.  A  number  of 
tests  were  run  at  the  U.  S.  Forest  Products  Laboratory  to  de- 
termine the  corrosive  action  on  steel  of  various  wood  preserva- 
tives. A  strip  of  flange  steel  of  the  quality  specified  by  the 

1  Circular  188,  U.  S.  Forest  Service,  by  C.  H.  Teesdale.     The  Volatili- 
zation of  Various  Fractions  of  Creosote  after  Their  Injection  into  Wood. 

2  See  circulars  98  and  199,  U.  S.  Forest  Service. 

8  "Tests  to  Determine  the  Commercial  Value  of  Wood  Preservatives," 
by  H.  F.  Weiss,  Eighth  International  Congress  of  Applied  Chemistry. 


PRESERVATIVES  USED  IN  PROTECTING  WOOD          69 

American  Society  for  Testing  Materials,  August  16,  1909,  was 
submerged  in  the  preservative  and  heated  to  a  constant  tem- 
perature of  about  98°  C.  jThe  preservative  was  changed  every 
week  for  four  weeks  in  the  cq$e  of  oils;  with  aqueous  solutions  it 
was  changed  every  day  for  one  week.  The  difference  in  the 
weight  of  the  steel  before  and  after  submersion  was  taken  to 
indicate  its  corrosion.  All  depositions  on  the  surface  of  the 
metal  were  removed  as  nearly  as  possible  with  a  rubber  "  police- 
man" each  time  the  preservative  was  changed.  At  the  end  of 
the  test,  where  electrolytic  deposition  of  metal  had  taken  place, 
the  deposited  metal  was  removed  by  acid  and  its  amount 
determined  by  an  analysis  of  the  acid  solution.  The  deposited 
metal  thus  obtained  was  added  to  the  loss  of  iron  and  this  total 
represented  the  total  corrosion.  The  corrosive  action  of  the 
various  preservatives  tested  is  shown  in  Table  5. 

The  odor  of  the  preservative  sometimes  influences  its  use, 
particularly  if  the  wood  is  to  be  placed  in  dwellings.  All  inorganic 
preservatives  are  practically  odorless  and  hence  not  objectionable 
on  this  account.  Many  of  the  organic  preservatives,  particularly 
the  " creosotes"  from  wood,  coal,  and  petroleum,  have  strong 
odors  which  are  quite  offensive.  If  allowed  to  air  season  thor- 
oughly before  being  placed  in  position  much  of  the  odor  can  be 
removed. 

It  frequently  happens  that  it  is  desirable  to  paint  wood  arti- 
ficially preserved.  This  is  particularly  the  case  with  wood  used 
in  dwellings,  greenhouses,  etc.  Creosoted  timber  cannot  be 
painted  satisfactorily  with  any  of  the  lighter  pigments,  but 
practically  'all  of  the  salts  are  free  from  this  objection.  Two 
other  factors  of  practical  significance  in  determining  the 
value  of  a  chemical  for  wood  preserving  purposes  are  the  effect 
the  preservative  has  on  the  strength  of  the  wood  treated  with  it, 
and  the  ability  of  the  preservative  to  penetrate  the  wood.  If  the 
preservative  is  such  as  to  seriously  impair  the  strength  of  wood 
treated  with  it,  it  will  necessitate  the  use  of  larger  timbers  and 
hence  increase  the  cost  of  the  structure.  Moreover,  if  the 
preservative  is  of  such  a  nature  that  it  cannot  be  forced  into 
wood,  its  value  is  considerably  decreased  on  this  account,  because 
it  will  succeed  in  only  protecting  the  surface  of  the  wood.  Any 
injury  to  the  surface  will  therefore  result  in  exposing  the  un- 
treated interior.  Tests  to  secure  data  on  both  these  points  were 
conducted  at  the  U.  S.  Forest  Products  Laboratory  on  air- 


70 


THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


seasoned  hemlock.  Approximately  8  pounds  of  the  preservative 
per  cubic  foot  in  the  case  of  oils  and  1/2  pound  or  more  of 
the  dry  salt  in  the  case  of  water  solutions  were  forced  into  the 
wood  by  the  Bethell  process.  The  wood  was  then  permitted 
to  air  season  and  tested  in  bending  on  a  30,000-pound  testing 
machine,  the  strength  of  the  treated  pieces  being  compared  with 
that  of  the  untreated.  In  the  penetrance  tests  the  preservative 
was  forced  into  a  hole  bored  into  the  wood  under  a  constant  tem- 
perature of  180°  F.  and  pressure  of  80  pounds  per  square  inch  for 
30  minutes  when  oils  were  used  and  3  minutes  for  salt  solutions. 
The  sticks  were  then  sawed  and  the  depth  to  which  the  preserva- 
tives entered  was  measured.  The  results  of  both  these  tests  are 
shown  in  table  6. 

TABLE  6. — PENETRANCE   OF  THE  PRESERVATIVES  AND  THEIR  EFFECT  ON 
THE  STRENGTH  OF  WOOD 


Preservative 
designed  by 
manufacturer  as 

Penetration 

Average 
absorption  of 
preservative 

Strength  in  per- 
cent of  modulus 
of  rupture  of 
untreated  wood 

Untreated  „  g 

1  **  2. 

sture 
test 

Rad.  and 
tang. 

Long1 

1 

\ 

H 

Max. 

Min. 

Max. 

Min. 

Coal-tar  creosote  
S.P.F.  carbolineum  ..  . 
Avenarius      Carbolin- 
eum   

In. 

0.28 
0.37 

0.17 
0.03 
0.08 
0.10 
0.02 
0.22 
0.10 

0.25 
0.10 
0.10 
0.13 
0.05 
0.10 

In. 

0.23 
0.23 

0.12 
0.03 
0.08 
0.10 
0.02 
0.22 
0.083 

0.17 
0.08 
0.10 
0.10 
0.03 
0.10 

In. 

6.0 
6.0 

6.0 
0.92 
3.58 
6.0 
0.33 
6.0 
6.0 

6.0 
6.0 
6.0 
6.0 
0.46 
6.0 

In. 

5.3 

5.7  + 

5.3  + 
0.50 
2.33 
3.33 
0.33 
4.08 
5.3 

4.66 
4.66 
3.30 
4.6 
0.30 
5.00 

Lb.  per 
cu.  ft. 
8.76 
8.83 

8.08 
6.50 
2.82 
9.58 
5.68 
8.58 
0.432 

1.11 
0.96 
0.46 
0.50 
0.99 
0.20 

93 

% 
6.2 

% 

109 
98 
107 
108 
106 
101 
88 

82 
89 
103 

85 
82 
85 

6.81 
6.11 
5.8 
4.52 
6.68 
5.49 
7.13 

3.88 
5.14 
5.72 
5.16 
6.42 
5.  82" 

9.35 

5.77 
9.6 
6.58 
9.48 
7.38 
8.7 

Hardwood  tar  

Creosote  (Douglas  fir) 
1.07  oil  
Timberasphalt  
Copperized  oil  

Zinc  chloride  
Zinc      sulphate      (by- 
product   

Zinc  sulphate  
Creosol  calcium  
B.M.  preservative.  .  .  . 
Sodium  silicate  
Sodium  fluoride  

1  A  penetration  of  6  inches  was  the  maximum  that  could  be  secured.     The  absorptions 
here  given  have  no  reference  to  the  data  on  penetrance. 

2  Dry  salt. 

The  effect  of  the  preservative  in  the  wood  upon  the  inflamma- 
bility of  the  wood  is  also  an  important  consideration,  particularly 
in  mines,  bridges,  and  dwellings.  This  effect  is  described  at 
length  in  Chapter  XVI. 

It  can  be  seen  from  this  discussion  that  many  factors  aside  from 
cost,  ease  of  transporting,  etc.,  affect  the  practical  value  of  a 


PRESERVATIVES  USED  IN  PROTECTING  WOOD  71 

preservative,  and  that  no  one  preservative  possesses  all  the  re- 
quirements which  will  make  its  use  applicable  to  all  conditions. 
A  selection  is  therefore  imperative. 

The  preservatives  which  feave  most  conspicuously  succeeded 
in  fulfilling  the  above  requirements  may  be  logically  grouped  into 
three  classes,  (1)  water-soluble  preservatives,  (2)  crude  oils,  and 
(3)  creosotes. 

Water-soluble  Preservatives. — While  a  large  number  of  water- 
soluble  preservatives  have  been  tested,  only  a  few  have  proven 
of  any  practical  value.  Most  of  them  are  either  not  sufficiently 
toxic  against  fungi  or  form  reactions  with  the  wood  which  tend 
to  destroy  the  strength  of  the  wood.  This  latter  is  particularly 
the  case  with  iron  sulphate  and  chemicals  strongly  alkaline.  Of 
the  many  water-soluble  preservatives  tested,  copper  sulphate, 
mercuric  chloride,  sodium  flouride,  and  zinc  chloride  have  given 
best  results. 

Copper  Sulphate. — This  salt  was  first  put  to  extensive  use  by 
Margary  in  England  about  1837.  It  was  later  used  by  Boucherie 
in  France,  where  it  is  still  commonly  employed  in  treating  timber, 
particularly  poles.  It  is  strongly  toxic  against  wood-destroying 
fungi.  It  is  readily  soluble  in  water  and  easily  leaches  from  wood 
treated  with  it.  The  chief  objection  to  its  use  is  its  action  on 
iron,  the  copper  being  immediately  deposited.  It  cannot,  on 
this  account,  be  used  in  the  standard  type  of  timber-preserving 
plant.  It  is  comparatively  cheap,  costing  about  5  to  6  cents  per 
pound,  and  when  injected  into  wood  gives  good  results.  It  is 
almost  as  efficient  as  zinc  chloride,  poles  treated  with  it  in 
Germany  lasting  11.7  years  as  compared  with  similar  poles  treat 
ed  with  zinc  chloride  which  lasted  11.9  years.  One  desirable 
quality  is  the  ease  with  which  the  preservative  can  be  seen  in  the 
wood,  as  it  stains  the  wood  cells  a  distinct  green.  The  use  of  this 
salt  is  now  practically  confined  to  France.  The  amount  of  timber 
treated  with  it  in  the  United  States  is  insignificant.  It  is  believed, 
however,  to  have  distinct  merit,  particularly  for  the  treatment  of 
green  posts  and  poles.  (See  Boucherie  process  for  further 
discussion.) 

Mercuric  Chloride. — This  is  the  most  toxic  wood  preservative 
in  use.  It  was  first  extensively  employed  by  Kyan  in  England 
about  1832.  Extremely  small  quantites  of  this  salt  in  wood 
will  absolutely  kill  all  wood-destroying  fungi.  Its  toxic  limit  is 
even  below  that  of  such  toxic  salts  and  acids  as  potassium  di- 


72          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

chromate,  silver  nitrate,  hydrochloric  acid,  etc.  It  cannot  be 
safely  tested  with  agar  in  petri  dishes  since  it  unites  with  the  pro- 
teid  elements  of  the  agar. 

Magnin  and  Sternberg1  conducted  extensive  tests  with  various 
antiseptics  upon  the  septic  micrococcus,  with  the  following 
results : 

Corrosive  sublimate 1  part  in  40,000  prevented  development. 

Copper  sulphate 1  part  in  400  prevented  development. 

Zinc  chloride 1  part  in  200  prevented  development. 

Carbolic  acid 1  part  in  300  prevented  development. 

Mercuric  chloride  is  much  less  soluble  in  water  than  zinc 
chloride  or  copper  sulphate.  It,  unfortunately,  severely  attacks 
iron,  hence  its  use  is  debarred  in  modern  treating  plants.  Al- 
though it  is  expensive,  costing  about  70  cents  a  pound,  neverthe- 
less the  very  small  quantity  necessary  to  keep  wood  sound  does 
not  by  any  means  render  its  use  prohibitive.  On  account  of  its 
very  poisonous  nature,  solutions  of  mercuric  chloride  must  be 
handled  with  extreme  care  or  mercurial  poisoning  will  result. 
This  salt  is  not  in  extended  use  at  the  present  time  in  this  country 
but  is  employed  by  a  few  Kyanizing  works  in  New  England.  In 
India  and  Africa  it  is  reported  as  giving  very  good  results  against 
the  attacks  of  white  ants.  Poles  treated  with  it  in  Germany 
lasted  13.7  years  as  against  11.9  years  for  zinc-treated  poles. 

Sodium  Fluoride. — The  commercial  application  of  sodium 
fluoride  to  the  preservative  treatment  of  timber  is  comparatively 
recent.  It  has  been  tested  by  Malenkovic  in  Austria  for  the 
past  8  years  with  apparently  excellent  results.  It  is  more 
toxic  than  zinc  chloride  (see  Table  4)  and  is  not  so  readily  leached 
from  the  wood.  Its  corrosive  action  on  iron  is  also  slight,  being 
less  than  that  for  zinc  chloride,  so  that  it  can  be  used  in  modern 
timber -treating  plants.  Its  cost  is  also  comparatively  low,  being 
about  5  to  7  cents  per  pound.  No  records  are  known 
showing  the  use  of  sodium  fluoride  as  a  wood  preservative  in  the 
United  States.  Extensive  experiments,  which  have  thus  far 
yielded  very  satisfactory  results,  are  now  under  way  at  the 
U.  S.  Forest  Products  Laboratory  and  it  is  quite  likely  that  this 
salt  may  find  a  large  commercial  application  in  this  country. 

Zinc  Chloride. — About  20,000,000  pounds  of  zinc  chloride  are 
now  used  annually  in  the  United  States  in  treating  timber — an 
amount  which  makes  it  by  far  the  most  extensively  used  water- 

1  Boulton — The  Preservation  of  Timber,  1885. 


PRESERVATIVES  USED  IN  PROTECTING  WOOD  73 

soluble  salt.  It  was  first  employed  on  an  extensive  scale  by  Sir 
William  Burnett  in  England  about  1838  and  timber  is  now 
treated  with  it  in  all  the  larger  "European  countries.  Zinc  chloride 
is  very  toxic  against  wood-destroying  fungi,  offering  about  the 
same  resistance  as  coal-tar  creosote.  Its  chief  fault  is  its  solu- 
bility in  water,  which  property  renders  it  inadvisable  to  use 
zinc-treated  timbers  in  wet  localities.  In  localities  which  are 
not  excessively  wet,  the  zinc  chloride  will  remain  in  the  timber  for 
many  years.  Numerous  cases  are  on  record  which  show  zinc- 
treated  ties  have  remained  durable  for  10  or  more  years,  while 
the  untreated  failed  in  4  to  5  years.  It  appears  from  various 
analyses  which  have  been  made  that  certain  amounts  of  zinc 
chloride  injected  into  wood  combine  with  the  wood  forming  a 
compound  insoluble  in  water.  Whether  or  not  this  combined 
zinc  chloride  is  toxic  has  not  yet  been  definitely  determined. 
If  it  is  not,  it  probably  is  of  little  or  no  value  in  preserving  the 
wood. 

Zinc  chloride  will  also  corrode  iron,  although  the  extent  to 
which  it  does  this  at  concentrations  used  in  treating  wood  is  so 
small  as  to  be  of  no  serious  moment.  It  is  customary,  however, 
to  figure  higher  depreciation  on  zinc-chloride  plants  than  on 
creosote  plants  due  to  its  more  corrosive  nature. 

The  cost  of  zinc  chloride  is  small,  being  about  4  or  5  cents  a 
pound.  Moreover,  the  quality  generally  produced  in  this 
country  is  of  very  high  grade,  far  superior  to  that  commonly  pro- 
duced abroad.  Zinc  chloride  is  purchased  fused  in  drums  of  500- 
or  1000-pound  capacity,  or  in  concentrated  (about  50  percent) 
solution.  When  in  high  concentration  the  solution  is  basic  and 
will  strongly  attack  wood,  reducing  it  to  a  pulp.  At  dilute  con- 
centrations the  solution  is  acid. 

Owing  to  its  importance  as  a  wood  preservative,  the  following 
specification  for  the  purchase  of  zinc  chloride  is  given.  It  is 
the  one  used  by  the  U.  S.  Forest  Products  Laboratory.  A 
similar  specification  is  in  use  by  the  American  Railway  Engineer- 
ing Association. 

"The  fused  zinc  chloride  must  contain  at  least  94  percent  of  water- 
soluble  chloride  of  zinc  and  it  must  be  slightly  basic;  that  is,  contain  no 
free  acids.  It  should  be  practically  free  from  soluble  iron  and  in  no  case 
will  it  have  more  than  0.022  percent  of  this  element.  It  shall  not  con- 
tain more  than  one-half  of  1  percent  of  other  inorganic  impurities  in- 
soluble in  hydrochloric  acid." 


74  THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Although  several  methods  have  been  suggested  for  determining 
the  amount  of  zinc  chloride  injected  into  wood,  the  following  is 
believed  to  be  the  most  accurate  and  satisfactory.1 

The  material  to  be  analyzed  is  first  dried  in  the  form  of  discs  or  sec- 
tions and  should  be  a  fair  average.  The  discs  are  then  reduced  to  saw- 
dust and  5  grams  are  weighed  into  a  500  c.c.  short-neck,  round-bottom 
Jena  boiling  flask:  50  c.c.  of  a  previously  prepared  saturated  solution  of 
potassium  chlorate  in  concentrated  nitric  acid  is  then  added  in  the  cold 
and  mixed  into  it  by  a  vigorous  shake.  A  violent  reaction,  accompanied 
by  the  evolution  of  considerable  heat,  immediately  takes  place  but  sub- 
sides after  a  few  minutes  leaving  a  wine-colored  solution  in  which  parti- 
cles of  partly  digested  wood  are  floating.  When  cool,  10  c.c.  of  concen- 
trated sulphuric  acid  (sp.  gr.  1.8)  are  added  and  the  solution  again  shaken. 
This  dissolves  all  the  wood  substance.  The  solution  is  then  boiled. 
More  potassium  chlorate-nitric  acid  solution  is  added  and  the  solution 
kept  boiling  until  no  further  charring  occurs  on  evaporation  to  sulphuric 
acid  and  the  solution  remains  a  pale  yellow.  When  cool,  it  is  diluted 
with  100  c.c.  of  water;  10  c.c.  of  dilute  nitric,  10  c.c.  of  2  percent  ferric 
chloride  solution,  and  1  gram  of  citric  acid  are  then  added,  and  the  solu- 
tion again  allowed  to  cool.  After  cooling  it  is  neutralized  with  ammo- 
nia leaving  it  slightly  ammoniacal.  The  volume  is  brought  up  to  200 
c.c.  and  the  temperature  to  80°  C.  at  titration.  The  standard  solution  of 
potassium  ferrocyanide  is  then  run  in  from  the  burette  until  a  drop  of 
the  titrated  solution  when  placed  in  the  center  of  1  c.c.  of  the  glycerine 
acetic  acid  indicator  leaves  a  permanent  greenish-blue  ring.  At  this 
point  the  titration  is  complete.  Calculations  are  then  made  from  the 
analytical  data.  To  calculate  the  results  in  pounds  of  zinc  chloride  per 
cubic  foot  of  wood,  the  specific  gravity  of  the  wood  must  be  known  to 
within  0.005.  Then  multiply  this  specific  gravity  to  62.5  and  this  prod- 
uct by  the  percentage  weight  of  zinc  chloride  found  by  analysis  to 
obtain  the  amount  of  zinc  chloride  per  cubic  foot  of  wood. 

If  knowledge  of  the  actual  amount  of  zinc  is  not  desired,  but 
simply  an  idea  of  how  deeply  it  has  penetrated,  two  methods  are 
suggested.  One  is  to  cut  a  section  through  the  stick  to  be  ex- 
amined and  dry  it  thoroughly  in  a  drying  oven  heated  to  100°  C. 
until  all  water  has  been  evaporated.  The  wood  will  be  turned  a 
deep  brown  wherever  the  zinc  chloride  has  penetrated.  A 
second  method  is  to  dip  the  freshly  cut  disc  of  treated  wood  for  a 
few  seconds  in  a  1  percent  potassium  ferrocyanide  solution. 
Remove  the  excess  solution  with  a  blotting  paper  and  redip  the 
disc  into  a  1  percent  solution  of  uranium  acetate.  On  drying, 

1  Method  developed  by  Bateman,  U.  S.  Forest  Products  Laboratory. 


PRESERVATIVES  USED  IN  PROTECTING  WOOD  75 

the  untreated  portion  of  the  wood  will  have  a  dark  red  color  while 
the  treated  portion  will  be  much  lighter. 

Crude  Oils. — Crude  oils  are"  not  widely  used  in  treating  timber 
in  our  country.  They  rely  uj|pn  their  ability  to  preserve  wood  on 
their  tendency  to  " waterproof"  it  and  thus  keep  it  too  dry  for 
wood-destroying  fungi.  The  oils  are  all  practically  nontoxic 
although  some  of  them  are  slightly  poisonous  to  fungi.  In  order 
to  "waterproof"  the  wood  it  is  necessary  to  force  comparatively 
large  quantities  of  the  oil  into  it.  This  makes  crude-oil  treated 
timber  quite  heavy  and  very  liable  to  drip  oil,  especially  if  ex- 
posed to  a  hot  atmosphere. 

Three  varieties  of  " crude  oil"  are  in  use,  viz.,  crude  oil  with  a 
paraffin  base,  crude  oil  with  an  asphaltic  base,  and  residuum, 
which  is  a  product  of  petroleum  distillation.  All  these  crude 
oils  have  a  gravity  less  than  water,  whereas  all  creosotes  are 
heavier  than  water.  Crude  oils  with  a  paraffin  base  are  found  in 
large  quantities  in  Ohio,  Pennsylvania,  and  other  states.  They 
are  usually  lighter  in  color  and  gravity  than  the  oils  with  an  as- 
phaltic base.  These  latter  oils  occur  in  California  and  part  of 
Texas.  Residuum,  which  is  the  heavy,  rather  viscous  oil 
remaining  after  the  distillation  of  the  lighter  portions  of  the 
crude  oil,  varies  in  gravity  and  viscosity  according  to  the  method 
of  manufacture.  If  too  viscous,  it  cannot  be  made  to  penetrate 
wood.  It  is  best,  therefore,  when  it  contains  a  fairly  large 
percentage  of  lighter  constituents.  None  of  the  crude  oils 
penetrate  coniferous  woods  as  readily  as  creosote.  This  may  be 
due  in  a  large  measure  to  their  inability  to  dissolve  the  resin  in  the 
wood  as  is  done  by  creosote.  The  price  of  crude  oils  varies  from 
about  2  to  5  cents  per  gallon.  In  treating  timber  with  crude 
oil  it  is  customary  to  force  as  much  oil  into  the  wood  as  it  is 
possible  to  get  in — an  amount  which  varies  of  course  with  the 
different  woods.  If  12  pounds  of  oil  per  cubic  foot  can  be 
retained  in  the  wood,  a  heavy  impregnation  has  been  secured. 

Creosotes.1 — Owing  to  their  ability  in  preserving  wood, 
creosotes  will  be  discussed  in  detail,  as  they  are  the  most  im- 
portant preservatives  now  known. 

Much  misunderstanding  exists  as  to  the  meaning  of  the  term 
" creosote."  It  is  defined  by  the  Standard  Dictionary  as  "a 
colorless  to  yellowish  oily  liquid  compound  consisting  of  a  mixture 

1  The  data  given  on  creosotes  is  largely  taken  from  Circular  206,  U.  S 
Forest  Service — "Commercial  Creosotes" — by  Carlile  P.  Winslow. 


76          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

of  phenols  distilled  from  wood,  and  having  a  smoky  odor  and 
burning  taste.  It  is  a  powerful  antiseptic  and  is  used  for  the 
preservation  of  timber,  meat,  etc. ;  called  also  oil  of  wood-tar  and 
oil  of  smoke."  Allen,  in  his  Commercial  Organic  Analysis, 
says:  "The  name  'kreosot'  was  first  applied  by  Reichenbach, 
in  1832,  to  the  characteristic  antiseptic  principle  contained  in 
wood-tar.  Carbolic  acid  was  discovered  soon  after  by  Runge  in 
coal-tar,  and  was  long  confused  with  the  wood-tar  principle; 
and  the  crude  carbolic  acid  from  coal-tar  is  still  known  as  'coal- 
tar  creosote/  Somewhat  similar  products  are  now  obtained  from 
other  sources,  so  that  much  confusion  has  arisen.  The  term 
'creosote/  when  used  without  qualification,  ought  to  be  under- 
stood as  signifying  the  product  from  wood-tar,  but  it  is  better 
to  describe  Reichenbach's  body  as  'wood-tar  creosote/  and  em- 
ploy the  unqualified  word  'creosote'  in  a  generic  sense  as  meaning 
the  mixed  phenols  and  phenoloid  bodies  obtained  from  wood-tar, 
coal-tar,  blast-furnace  tar,  shale  oil,  bone  oil,  or  other  sources." 

In  its  original  meaning,  therefore,  the  term  "creosote"  was 
applied  to  a  product  obtained  from  wood,  and  the  term  is  still 
used  thus  in  pharmacy,  and  refers  to  a  refined  product  derived 
from  ;the  destructive  distillation  of  beech  or  other  hardwood. 
However,  with  the  development  of  both  the  wood-preserving 
and  the  coal-tar  industries,  the  term  "creosote  oil,"  frequently 
abbreviated  to  "creosote,"  gradually  came  to  be  applied  to  the 
heavy  distillates  from  coal-tar,  and  the  use  of  the  term  has  be- 
come more  and  more  extended  until,  at  the  present  time,  it  is 
commonly  used  in  referring  to  the  distillates  heavier  than  water 
from  any  tars  or  tar-like  substances,  alid  is  even  erroneously  used 
to  cover  products  containing  admixtures  of  undistilled  tar  or 
pitch.  As  a  result  of  this  lax  use  of  the  word  it  conveys  but  little 
to  those  conversant  with  the  subject  and  is  confusing  to  those 
unfamiliar  with  commercial  practice.  More  specific  terms  are 
evidently  needed  to  properly  differentiate  between  the  various 
creosotes.  The  most  useful  classification  from  the  wood  pre- 
server's point  of  .view  would  be  one  based  upon  the  merits  of  the 
various  products  but  lack  of  sufficient  data  renders  this  impossible 
at  this  time.  The  most  practical  classification  at  present  must 
be  based  upon  the  source  and  method  of  production.  The 
following  terms  and  definitions  are  suggested: 

1.  Creosote  is  a  distillate  heavier  than  water  obtained  by  the 
distillation  of  a  tar  or  a  tar-like  substance. 


PRESERVATIVES  USED  IN  PROTECTING  WOOD  77 

2.  Coal-tar  creosote  is  a  creosote  derived  from  coal-tar  pro- 
duced by  the  destructive  distillation  of  coal  at  a  temperature  high 
enough    to   produce   a   tar  'consisting,   for  the  most  part,  of 
hydrocarbons  of  the  aromatic,  series.1 

3.  Oil -tar  creosote2   (water-gas  tar  creosote)   is  a  creosote 
derived  from  oil  tar.     This  tar  may  be  obtained  from  the  de- 
structive distillation  of  petroleum  in  a  gas    retort,  producing 
oil-gas  as  a  main  product  and  oil-gas  tar  as  a  by-product,  or  by 
the  cracking  of  gas  oil  in  the  carburetor  of  a  water-gas  plant  pro- 
ducing carbureted  water-gas  as  a  main  product,  and  carbureted 
water-gas  tar  as  a  by-product. 

4.  Wood -tar  creosote  is  a  creosote  derived  from  a  tar  produced 
by  the  destructive  distillation  of  wood. 

5.  Mixed   creosote  is  a  creosote   produced   by   mixing  other 
material  with  a  given  creosote,  such  as  another  creosote,  pitch, 
undistilled  tar,  or  petroleum,  or  it  may  be  secured  by  the  dis- 
tillation of  a  mixture  of  two  or  more  tars  on  tar-like  substances. 
In  view  of  the  similarity  between  certain  mixed  creosotes  and 
creosotes  obtained  by  the  distillation  of  coal-tar,  produced  at 
temperatures  sufficiently  low  to  permit  the  production  of  hydro- 
carbons of  the  paraffin  series,  these  latter  distillates  are  also 
classed  under  this  heading. 

Source  of  Tars. — Although  there  are  a  variety  of  tars  from 
which  creosotes  may  be  produced,  the  most  important  commercial 
ones  may  be  classified  as  coal-tars,  oil-tars,  and  wood-tars.  The 
sources  and  general  methods  of  production  of  these  tars  arenas 
follows : 

Coal-tars. — The  important  coal-tars  are  derived  chiefly  from 
two  sources:  The  destructive  distillation  of  bituminous  coal 
at  high  temperatures  and  the  combined  distillation  and  com- 
bustion of  bituminous  coal  at  comparatively  low  temperatures. 
The  first,  which  furnishes  by  far  the  greater  proportion  of 

1  Creosote  secured  from  coal- tar  produced  at  sufficiently  low  temperature  to 
permit  the  production  of  hydrocarbons  of  the  paraffine  series  might  also  be 
included  under  the  name  of  coal-tar  creosote,  but  in  view  of  the  paraffin 
hydrocarbons  it  is  classed  in  this  publication  as  mixed  coal-tar  creosote. 

2  Inasmuch  as  the  derivatives  of  oil-gas  tars  and  water-gas  tars  contain  no 
phenoloid  bodies,  the  use  of  the  term  " creosote"  in  this  connection  might, 
from  a  purely  technical  standpoint,  be  considered  erroneous.     However, 
the  term  is  used  commercially  at  the  present  time  in  this  connection,  and  a 
careful  consideration  of  the  various  definitions  used  in  this  publication 
should  prevent  any  misunderstanding. 


78          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  total  supply,  is  produced  in  the  manufacture  of  coke  and 
gas  in  by-product  retorts  and  gas-house  plants.  Bituminous 
coal  is  destructively  distilled  at  temperatures  varying  from 
1500°  F.  to  3000°  F.,  until  the  charge  has  been  reduced  to 
coke.  During  the  process  the  ammoniacal  liquor  and  tar  are 
separated  from  the  generated  gases  by  condensation  and  wash- 
ing. The  tars  naturally  vary  in  their  properties  according 
to  the  character  of  the  coal,  and  of  the  retorts,  and  according 
to  the  temperatures  used.  These  factors  in  turn  are  largely  de- 
pendent upon  which  of  the  two  main  products,  gas  or  coke,  is 
primarily  desired;  tar  acids,  however,  are  always  present  in  the 
tars  and  usually  the  temperatures  are  sufficiently  high  in  both 
cases  to  produce  tars  consisting  largely  of  hydrocarbons  of  the 
aromatic  series. 

Coal-tars  produced  at  relatively  low  temperatures  differ  from 
those  produced  at  higher  temperatures  in  the  character  of  their 
hydrocarbons.  Since  the  temperatures  are  not  high  enough  to 
transform  all  of  the  hydrocarbons  to  the  aromatic  series,  the 
tars  contain,  to  a  greater  or  less  extent,  hydrocarbons  of  the 
paraffin  group.  Tars  secured  from  blast  furnaces  using 
bituminous  coal  as  fuel  and  from  the  Mond  producer  plants,  where 
bituminous  coal  is  used  in  the  manufacture  of  gas  for  power 
purposes,  are  representative  of  this  group.  The  production  of 
such  tars,  however,  is  not  extensive  in  this  country. 

Oil-tars. — Of  the  oil  tars,  that  produced  in  the  manufacture 
of  water  gas  is  by  far  the  most  important  in  its  relation  to  the 
manufacture  of  creosote.  The  method  of  production  is,  in 
general,  as  follows:  The  " generator"  is  charged  with  coke  or 
anthracite  coal,  which  is  burned  by  the  aid  of  an  air  blast  to 
a  cherry  red.  The  hot  gases  so  formed  are  passed  through  the 
"carbureter"  and  " superheater,"  which  consists  of  vertical 
cylindrical  chambers  filled  with  a  checkerwork  of  fire  brick. 
After  these  bricks  are  heated  to  the  proper  temperature  the 
air  blast  is  discontinued  and  steam  is  blown  into  the  generator. 
The  gases  formed  by  the  contact  of  the  steam  with  the  hot  coke 
or  coal  pass  into  the  carbureter,  into  which  petroleum  "gas  oil" 
is  sprayed  at  the  same  time.  This  oil  is  partially  cracked  by  the 
high  temperature  of  the  fire  brick  and  combines  with  the  gases 
from  the  generator  to  increase  their  illuminating  power;  the 
process  of  cracking  continues  through  the  superheaters.  The  gas 
is  then  passed  to  the  condensers  and  washers,  where  tar  is  con- 


PRESERVATIVES  USED  IN  PROTECTING  WOOD  79 

densed  and  collected.  This  tar  differs  in  its  constituents  from 
coal-tar  produced  in  the  by-product  coke  ovens  and  gas  retorts 
both  in  the  absence  of  tar  acids  and  in  the  presence  of  .hydrocar- 
bons of  the  paraffin  series;  usually,  however,  the  quantity  of 
paraffin  hydrocarbons  present  is  comparatively  small. 

Some  oil-tar  also  is  produced  by  the  destructive  distillation 
of  crude  petroleum  in  the  manufacture  of  oil  gas.  In  tars  from 
this  source  the  quantity  of  paraffin  hydrocarbons  present  is 
generally  much  greater  than  in  that  produced  in  the  manufacture 
of  carbureted  water  gas. 

Wood-tars. — Wood-tar  is  produced  in  a  manner  somewhat 
similar  to  that  in  which  by-product  coal-tar  is  formed.  Wood  is 
destructively  distilled  in  retorts,  and  charcoal  is  produced,  together 
with  gas  and  a  liquid  distillate  which  consists  largely  of  pyro- 
ligneous  acid  and  a  product  called  crude  tar.  The  tar  and  acid 
are  separated  by  settling  and  by  distillation.  Wood-tars  are  quite 
different  from  coal-tars  and  contain,  in  particular,  less  of  the 
aromatic  hydrocaibons. 

Distillation  of  Creosote  from  Tars. — From  any  or  all  of  the 
foregoing  tars,  either  alone  or  in  mixture,  creosote  may  be  pro- 
duced. The  general  process  of  manufacture  is  similar  in  all 
cases.  The  tar  is  distilled  in  a  metal  retort  or  still  and  the  vapors 
are  condensed  and  collected.  Those  distillates  which  are  heavier 
than  water  form  the  true  creosotes  used  in  wood  preservation. 
The  temperatures  at  which  the  creosotes  are  obtained  vary  greatly, 
but  generally  lie  between  about  200°  and  360°  C.  The  actual 
temperatures  in  each  case  depend  largely  upon  the  character 
of  the  residue  desired.  In  the  United  States  the  manufacture 
of  creosote  from  coal-tar  is  generally  secondary  to  the  manu- 
facture of  soft  pitch ;  and  in  such  cases  the  maximum  tempera- 
ture during  the  distillation  is  comparatively  low.  In  Europe, 
on  the  other  hand,  coal-tar  is  distilled  largely  for  the  production 
of  the  coal-tar  dyes,  and  the  distillation  is  carried  to  higher  tem- 
peratures. The  creosote,  therefore,  contains  a  relatively  greater 
amount  of  the  higher  boiling  constituents  than  the  American 
product. 

As  already  stated,  pitch,  undistilled  tar,  or  other  similar  mate- 
rials are  frequently  mixed  with  a  creosote,  and  while  such  mixtures 
are  sometimes  sold  as  creosotes,  the  term  is  improperly  applied 
except  as  it  relates  to  the  distilled  product. 

The  complexity  of  the  many  hydrocarbons   and  their  de- 


80          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

rivatives  which  may  be  produced  in  the  destructive  distillation 
of  coal,  oil,  and  wood  makes  it  impossible  to  state  precisely  the 
nature  of  the  various  constituents  of  all  creosotes.  However, 
they  may  be  broadly  divided  into  two  classes,  compounds  of  the 
aromatic  series  and  compounds  of  the  paraffin  series.  The 
characteristic  difference  between  the  two  lies  in  the  greater  chemi- 
cal activity  of  the  former.  Coal-tar  creosote  consists  almost 
wholly  of  aromatic  compounds,  and  the  long  period  of  successful 
use  of  such  creosote  has  led  to  the  general  feeling  that  these  con- 
stituents are  the  more  desirable. 

The  compounds  of  the  aromatic  series  may  be  divided  into 
three  groups,  as  follows:  (1)  "Light  oils,"  which  distill  below 
205°  C.  and  consist  largely  of  phenols  and  cresols,  or  tar  acids; 
(2)  naphthalenes,  which  distill  between  approximately  205° 

Bituminous  Coal 


I 

Tar  Coke 


I 

Oils  Lighter  than  Water  Oils  Heavier  Pitch 

than  Water 
Creosote 

Distillation  Limits  and  General  Nature  of  the  Aromatic  Constituents 


Light  Oils 
|      Rich  in  Phenols 

Naphthalenes 

Constituents  of  an  Anthracene  Nature 

Liquid  at  Room 
Temp. 
205 

Solid  at  Room 
Temp. 
C.                                   25 

Liquid  at  Room 
Temp. 
5°C.                                       28 

Solid  at  Room 
Temp. 
5°C.                           380  ' 

FIG.  6. — Derivation  of  coal-tar  creosote. 

and  255°  C.;  and  (3)  constituents  of  an  anthracene  nature  dis- 
tilling above  255°  C.,  which  will  be  referred  to  collectively 
as  "  anthracenes."  Some  or  all  of  these  are  found  in  most 
creosotes. 

Of  these  constituents  the  tar  acids  possess  the  highest  anti- 
septic properties;  they  are,  however,  soluble  in  water  and  are 
more  volatile  than  the  other  constituents.  The  naphthalenes  and 
anthracenes  are  neither  so  antiseptic  nor  so  volatile  as  the  tar 
acids  and  are  practically  insoluble  in  water.  There  is  much 
discussion  as  to  the  relative  value  of  these  different  constituents, 
but,  largely  as  a  result  of  experience,  the  presence  of  tar  acids  is 
believed  by  many  to  be  essential.  While  a  large  proportion  of 
naphthalene  is  sometimes  advocated,  particularly  for  the  pres- 
ervation of  piling,  a  reduction  in  the  quantity  of  this  constituent, 


PRESERVATIVES  USED  IN  PROTECTING  WOOD  81 

with  a  corresponding  increase  in  the  amount  of  anthracenes,  is 
believed  to  increase  the  value  of  a  creosote  for  general  purposes. 

Coal-tar  Creosote. — Fig.  6 L- shows  graphically  the  derivation 
and  general  composition  of  coal-tar  creosote.  The  relative 
quantity  of  tar  acids,  naphtttalenes,  and  anthracenes  will  of 
course  vary  according  to  the  character  of  the  tar  and  the  tem- 
peratures used  during  its  distillation,  but  generally  the  tar  acids 
present  will  not  exceed  5  percent,  the  naphthalenes  will  comprise 
from  15  to  50  percent,  and  the  anthracenes  will  comprise  the 
remainder.  As  previously  defined,  it  contains  practically  no 
paraffin  hydrocarbons.  The  creosote  as  a  whole  is  antiseptic, 
insoluble  in  water,  and  somewhat  volatile;  it  is  sufficiently  free 
from  "free  carbon/'  and  fluid  enough  at  temperatures  used  in  com- 
mercial treating  plants,  to  offer  no  great  resistance  to  entrance 
into  the  wood. 

Tests  made  at  the  U.  S.  Forest  Products  Laboratory  show  the 
toxic  limit  of  coal-tar  creosote  to  be  between  0.2  and  0.4  per 
cent.  Very  small  amounts  of  it  will  therefore  protect  wood  from 
decay.  In  general,  the  lighter  fractions  are  more  toxic  than  the 
heavier  fractions.  They  are  also  far  more  volatile  and  when 
injected  into  wood  by  themselves  evaporate  at  a  rapid  rate  (Fig. 
30).  The  heavier  constituents  of  coal-tar  creosote  are  there- 
fore, in  addition  to  being  slightly  toxic,  of  direct  value  in  helping 
to  retain  in  the  wood  these  lighter  oils.  The  permanency  of 
the  heavier  oils  is  well  illustrated  by  an  analysis  made  of  a  pile2 
in  actual  service  in  the  Gulf  of  Mexico  for  30  years.  This  pile 
was  cut  into  three  sections,  samples  from  which  were  then  ex- 
tracted for  creosote,  with  the  results  shown  in  Fig.  7. 

Numerous  similar  examples  could  be  cited,  all  of  which  show 
that  the  lighter  fractions  of  coal-tar  creosote  are  not  permanent. 
While  considerable  heated  discussion  has  occurred  as  to  their 
value,3  it  is  the  author's  opinion  that  these  lighter  oils  have 
distinct  merit  in  prolonging  the  life  of  timber,  and  if  they  had 
been  absent  entirely  from  the  creosote,  it  is  doubtful  if  such  long 
periods  of  service  could  have  been  secured. 

1  In  Figs.   6  and  8  the  term    "solid  at  room  temperature"  (20°  C.)  is 
used  in  describing  the  condition  of  certain  of  the  fractions  distilled  from 
creosote,  when,  at  the  ordinary  temperature  of  a  room,  they  retained  their 
position  in  the  receiving  flask  when  vigorously  shaken. 

2  U.  S.  Forest  Service  Circular  199,  "Quantity  and  Quality  of  Creosote 
Found  in  Two  Treated  Piles  after  Long  Service,"  by  E.  Bateman. 

3  "The  Preservation  of  Timber,"  by  S.  B.  Boulton,  1885. 


82 


THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


Coal-tar  creosote  does  not  corrode  iron  to  any  appreciable 
degree  (see  Table  5)  and  for  this  reason  is  admirably  adapted 
for  use  in  the  steel  cylinders  of  modern  timber  treating  plants. 

When  heated,  the  vapors  arising  from  the  oil  may  attack  the 
skin  and  cause  a  very  irritating  swelling  and  burning.  This 
effect  is  not  produced  on  most  people,  but  complaints  have  been 


80 


70 


GO 


50 


S  40 


20 


10 


f- 


X 


200  210  220  230  240  250  260  270  280  290  300  310  320  330  340 
Temperature  "Centigrade 

Legend 

•  Creosote  taken  from  Section  in  the  Mud 
O  Creosote  taken  from  Section  in  the  Water. 
O  Creosote  taken  from  Section  above  the  Water 

FIG.  7. — Distillation  of  creosote  remaining  in  a  pile  after  30  years'  service. 

made  by  workers  who  come  in  contact  with  creosoted  timber, 
particularly  trackmen,  and  several  law  suits  have  resulted.  Even 
the  cold  oil  may  produce  such  an  injury.  It  is  not,  however, 
serious  and,  with  caution  in  handling  the  treated  timber,  even  a 
sensitive  person  can  become  immune  to  any  discomfort. 

The  price  of  coal-tar  creosote  varies  considerably  and  for  the 
past  few  years  has  been  steadily  rising.     In  large  quantities  the 


PRESERVATIVES  USED  IN  PROTECTING  WOOD  83 

average  price  in  eastern  United  States  is  now  about  6  to  9  cents 
per  gallon.  In  the  West,  the  price  is  from  two  to  three  times 
this  amount,  and,  in  small  orders,  even  more.  The  sharp 
demand  for  the  oil,  and  its  present  limited  production  give  little 
hope  that  the  price  will  lower^materially  in  the  immediate  future. 
Much  discussion  has  occurred  concerning  the  quality  of 
creosote  best  suited  to  the  treatment  of  timber.  Until  recently 
discussion  has  resulted  in  little  practical  value  because  the 
demand  for  the  oil  was  so  great  the  consumer  was  glad  to  receive 
most  any  kind  he  could  get.  Now,  however,  several  grades  of 
coal-tar  creosote  can  be  obtained,  but  no  uniformity  exists  as 
yet  as  to  the  quality  best  suited  to  preserve  wood.  Most  authori- 
ties agree  that  a  comparatively  heavy  grade  is  better  than  a  light 
grade.  The  specifications  which  are  perhaps  in  most  extended 
use  at  present  in  the  United  States  are  the  ones  adopted  by  the 
American  Railway  Engineering  Association.  They  allow  three 
grades  of  oil,  the  specifications  reading  as  follows : 

"Grade  1  Oil. — The  oil  used  shall  be  the  best  obtainable  grade  of  coal- 
tar  creosote ;  that  is,  it  shall  be  a  pure  product  obtain  ed  from  coal  gas 
tar  or  coke  oven  tar  and  shall  be  free  from  any  tar,  oil  or  residue  ob- 
tained from  petroleum  or  any  other  source,  including  coal  gas  tar  or 
coke  oven  tar;  it  shall  be  completely  liquid  at  38°  C.  and  shall  be 
free  from  suspended  matter;  the  specific  gravity  of  the  oil  at  38°  C. 
shall  be  at  least  1 . 03  when  distilled  by  the  common  method — that  is, 
using  an  8  ounce  retort,  asbestos  covered,  with  standard  thermometer, 
bulb  1  /2  inch  above  the  surface  of  the  oil — the  creosote,  calculated  on  the 
basis  of  the  dry  oil,  shall  give  no  distillate  below  200°  C.,  not  more  than 
5  percent  below  210°  C.,  not  more  than  25  percent  below  235°  C.  and  the 
residue  above  355°  C.  if  it  exceeds  5  percent  in  quantity,  shall  be  soft. 
The  oil  shall  not  contain  more  than  3  percent  water." 

Grade  2  oil,  which  is  considered  "next  best,"  is  similar  to  the 
"standard"  just  quoted  except  for  the  amount  of  fractions  dis- 
tilled at  varying  temperatures,  these  being  "  not  more  than  8  per- 
cent below  210°  C.  and  not  more  than  35  percent  below  235°  C." 

Grade  3,  which  is  poorer  than  Grade  2,  differs  from  it  only 
in  specific  gravity  and  the  amount  of  distillates  at  various  tem- 
peratures, these  differences  being  "the  specific  gravity  at  38°  C. 
shall  be  at  least  1.025.  Not  more  than  10  percent  of  the 
oil  shall  distill  below  210°  C.;  not  more  than  40  percent  below 
235°  C." 

The  specification  in  use  by  the  U.  S.  Forest  Service  is  slightly 


84          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

more  rigid  than  the  above,  particularly  as  regards  the  method 
of  analyzing  the  oil  (see  appendix).  Most  of  the  confusion  which 
has  occurred  concerning  the  proper  kind  of  creosote  to  use  has 
come  through  lack  of  definite  data.  Commercial  motives  and 
an  attempt  on  the  part  of  certain  "experts"  to  mystify  the  trade 
have  also  added  to  the  complexity  of  the  situation.  In  all 
probability,  as  experience  grows  the  situation  will  clear  and 
specifications  for  coal-tar  creosote  will  be  drawn  depending  on  the 
use  to  which  the  oil  is  to  be  put.  Until  such  data  is  available 
the  safest  course  to  pursue  is  to  demand  a  comparatively  heavy 
oil  of  known  purity. 

In  treating  paving  blocks  a  heavy  oil  is  generally  used,  the 
idea  being  that  it  will  stay  in  the  wood  and  will  have  a  marked 
waterproofing  effect.  Thus  the  "  Association  for  Standardizing 
Paving  Specifications"  adopted  in  1911  the  following  grade  of  oil: 


Coke  or  Anthracite 
Steam  and 
Petroleum 

ar 

1 
Gas                                                             1 

r 

Oils  Lighter                    Oils  Hea 
than  Water                        Water  ( 

1 

vier  than                    Pitch  or  Coke 
Creosote 

General  Distillation  Limits  of  the  Constituents 


[Possibly 
Naphthalene 

Possibly  of  an  Anthracene  Nature  but  Generally 
containing  Paraffin  Hydro  Carbons 

Solid  at  Boom 
Temp. 
C.                            255  ( 

Liquid  at  Room            Liquid  at  Room             Solid  at  Room 
Temp.                            Temp.                          Temp. 
3.                                 295°C.                               34i°C. 

300' 

FIG.  8. — Derivation  of  water-gas-tar  creosote. 

"The  preservative  to  be  used  shall  be  a  coal-tar  product,  free  from 
adulteration  of  any  kind  whatever,  and  shall  comply  with  the 
following  requirements.  (1)  The  specific  gravity  shall  be  not  less 
that  1.10  or  more  than  1.14,  at  a  temperatute  of  38°  C.  (2)  Not 
more  than  3J  percent  of  the  oil  shall  be  insoluble  by  hot  continu- 
ous extraction  with  benzol  and  chloroform.  (3)  On  distillation, 
which  shall  be  made  exactly*  as  described  in  Bulletin  95  of  the 
American  Railway  Engineering  and  Maintenance  of  Way  Associa- 
tion, the  distillate  shall  not  exceed  2  percent  up  to  150°  C.  and 
shall  be  not  less  than  30  or  more  than  40  percent  up  to  315°  C." 
It  is  thus  apparent  that  the  oil  need  not  be  a  coal-tar  "creosote" 
and  must  contain  a  considerable  amount  of  the  heavier  con- 


PRESERVATIVES  USED  IN  PROTECTING  WOOD          85 

stituents  in  coal-tar  in  order  to  have  the  gravity  required.  This 
matter  is  also  discussed  in  Chapter  XIII. 

Water-gas-tar  Creosote. — Of  the  oil-tar  creosotes,  that  from 
water-gas  tar  is  practically  the  only  one  used  for  wood  preserva- 
tion. Fig.  8  illustrates  its  (Derivation  and  general  composition. 
This  creosote  is  not  ftiore  volatile  nor  soluble  in  water  than  coal- 
tar  creosote,  contains  no  "free  carbon,"  and  offers  no  marked  re- 
sistance to  entrance  into  the  wood.  In  fact,  water-gas-tar 
creosote  may  be  produced  which  on  fractional  distillation  will 
display  a  great  similarity  to  coal-tar  creosote.  There  is  a  dif- 
ference, however,  in  the  constituents  of  the  two  creosotes,  as 
shown  by  the  difference  in  certain  physical  properties  of  fractions 
distilled  from  them  at  equal  temperatures.  Furthermore,  water- 
gas-tar  creosote  is  distinctive  in  the  absence  of  phenols  and  cre- 
sols,  and  usually  in  the  presence  of  hydrocarbons  of  the  paraffin 
group;  it  is  not  so  antiseptic  as  coal-tar  creosote.  Unfortunately, 
quantities  of  this  oil  are  mixed  with  coal-tar  creosote,  so  that  it  is 
often  impossible  in  practice  to  detect  its  presence.  While  this 
oil  undoubtedly  has  considerable  merit  as  a  preservative  of  timber, 
there  is  not  sufficient  precise  data  available  to  warrant  giving  it  the 
confidence  which  the  coal-tar  product  now  enjoys.  Careful  tests 
show  its  toxicity  to  be  about  3  to  4  percent  as  compared  with  coal- 
tar  creosote,  which  has  a  toxic  limit  of  from  0.2  to  0.4  percent. 
The  most  reliable  tests  known  to  the  author  were  made  by  the 
U.  S.  Forest  Service  in  treating  mine  timbers  (see  Chapter  XII) 
which  failed  to  last  as  long  as  similar  timbers  treated  with  the 
coal-tar  creosote. 

Although  it  is  slightly  more  corrosive  of  iron  than  creosote  from 
coal-tar,  its  action  is  so  slight  that  its  use  in  steel  cylinders  can- 
not be  considered  objectionable  on  this  account. 

The  price  of  water-gas-tar  creosote  is  seldom  quoted  but  it  is 
generally  a  cent  or  two  a  gallon  less  than  the  coal-tar  product. 
There  is  no  doubt  but  that  much  of  this  oil  is  sold  as  a  coal-tar 
creosote  either  alone  or  in  combination  and  as  such  commands 
the  same  price. 

The  National  Electric  Light  Association  is  the  only  association 
known  to  the  author  which  has  framed  a  specification  for  water- 
gas-tar  creosote  to  be  used  in  preserving  wood.  This  specifica- 
tion reads  as  follows: 

"It  shall  have  a  specific  gravity  of  at  least  1.03  and  not  more  thanl-08 
at  38°  C.  There  shall  be  not  over  1  percent  of  residue  insoluble  in  hot 


86          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

benzol.  The  oil  shall  contain  not  over  2  percent  of  water.  The  residue 
remaining  upon  sulphonating  a  portion  of  the  total  distillate  shall  not 
exceed  5  percent.  When  200  grams  of  the  oil  are  distilled  in  accordance 
with  the  requirements  of  the  specifications  for  the  analysis  of  water  gas 
tar,  dead  oil  or  water-gas-tar  creosote  and  the  results  calculated  to  water 
free  oil  (a)  not  more  than  2  percent  of  oil  shall1  distill  off  up  to  205°  C., 
(b)  not  more  than  10  percent  shall  distill  off  up  to  235°  C.,  (c)  not  more 
than  60  percent  shall  distill  off  up  to  315°  C.,  (d)  the  coke  residue  shall  not 
exceed  2  percent." 

The  method  of  analysis  referred  to  calls  for  a  300  c.c.  side-neck 
Lunge  distilling  flask  provided  with  a  trap.1 

Wood-tar  Creosote. — Of  the  wood-tar  creosotes,  that  most  used 
in  the  past  has  been  secured  from  resinous  woods.  The  derivation 

Resinous  Woods 


I 

Gas  Liquid  Distillate  Charcoal 


Pyroligneous  Acid  Crude  Tar 


Oils  Lighter  than  Water 
Turpentine 


Pitch  or  Tar 


Oils  Heavier  than  Water. 
Creosote 


FIG.  9. — Derivation  of  wood-tar  creosote. 

of  such  creosotes  is  illustrated  in  Fig.  9.  Lack  of  authentic  data 
prevents  even  a  general  statement  as  to  its  constituents,  but  the 
proportion  of  tar  acids  and  volatile  constituents  is  generally  great- 
er, and  of  naphthalene  and  anthracene  much  less,  than  in  the  coal- 
tar  creosotes.  Wood-tar  creosotes  have  been  used  to  some  extent 
as  wood  preservatives  for  many  years.  They  are,  as  a  rule,  not  as 
toxic  as  coal-tar  creosote,  their  resistance  being  from  about  10  to 
50  less  than  the  coal-tar  product. 

On  account  of  the  comparatively  large  amount  of  acids  which 
they  contain,  they  corrode  iron  to  a  much  greater  extent  than  the 
coal-tar  oil  and  their  use  in  this  connection  may  be  considered 
objectionable.  It  is  but  fair  to  state,  however,  that  this  property 
could  be  largely  overcome  if  the  acids  were  removed  from  the 
oil.  Their  supply  has  been  so  limited  and  cost  so  comparatively 

1  Report  of  Committee  on  Preservative  Treatment  of  Poles  and  Cross- 
Arms,"  National  Electric  Light  Association,  June,  1911. 


PRESERVATIVES  USED  IN  PROTECTING  WOOD          87 

high  that  little  serious  attention  has  been  paid  to  them  except 
in  the  manufacture  of  certain  patented  products  and  "stains." 
The  rapid  rise  in  the  price  of  coal-tar  creosote  and  its  limited 
supply  have  of  late  attracted  considerable  attention  to  the 
creosotes  from  wood,  hence  it  is  likely  their  use  in  preserving 
wood  may  become  more  general  in  the  future. 

At  present  these  oils  are  rarely  quoted  below  12  cents  per 
gallon  even  in  large  quantities,  so  that  the  coal-tar  product  must 
rise  appreciably  or  the  price  of  the  wood-tar  oils  must  fall 
appreciably  before  their  extensive  use  will  occur.  In  addi- 
tion to  the  tars  from  resinous  woods,  there  is  no  good  reason 
why  the  tars  from  hard  woods  cannot  be  used  in  manufacturing 
creosotes.  If  this  is  done  a  larger  output  will  be  possible.  Just 
now,  no  stability  in  composition  is  recognized  in  wood  creosotes 
for  preserving  timber  and  hence  no  general  specification  for  them 
exists. 

Mixed  Coal-tar  Creosotes — A  large  part  of  the  creosote  pro- 
duced in  this  .country  falls  into  the  class  of  mixed  coal-tar 
creosote.  Some  is  made  by  the  mixture  of  undistilled  coal-tar, 
or  oil-tar,  or  pitch,  with  coal-tar  creosote ;  some  is  produced  by 
the  partial  distillation  and  combustion  of  bituminous  coal  at 
comparatively  low  temperatures;  and  some  is  secured  through 
the  manufacture  of  soft  pitch  when  coal-tar  and  water-gas  tar 
are  distilled  in  admixture.  The  nature  of  all  mixed  coal-tar 
creosotes  cannot  be  described,  because  their  constituents  and 
relative  merits  as  wood  preservatives  vary  in  each  case  accord- 
ing to  the  materials  used  in  their  production  and  preparation. 
Admixtures  of  undistilled  tar  or  pitch  containing  free  carbon 
will,  however,  tend  to  decrease  the  penetrance  of  the  creosote, 
while  the  admixture  of  products  which  contain  appreciable 
amounts  of  constituents  of  the  paraffin  series  will  doubtless 
affect  in  some  measure  the  antiseptic  properties  of  the  creosote. 

Paints  and  Stains. — Wood  which  has  been  painted  with 
ordinary  paint  (usually  a  mixture  of  linseed  oil,  turpentine,  and 
an  inorganic  pigment)  such  as  is  used  in  decorating  buildings  is 
partially  protected  from  decay  because  it  is  rendered  partially 
waterproof.  The  spores  of  wood-destroying  fungi  will  not 
develop  readily  on  the  surface  of  painted  wood.  To  secure  best 
results  only  air-seasoned  wood  should  be  painted,  as  green  wood 
will  be  very  liable  to  surface  check  and  expose  the  untreated 
interior.  Furthermore  paint  will  not  adhere  as  well  to  green 


88          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

timber.  The  layer  of  paint  usually  adheres  to  the  surface  of 
the  wood  and  has  little  or  no  penetrating  power.  Moreover, 
it  is  generally  porous  so  that  certain  amounts  of  water  can  pass 
through  it.  Judged  as  a  preservative  of  timber,  ordinary 
paint  must  be  considered  inefficient  and  under  certain  conditions 
may  even  do  the  timber  more  harm  than  good,  as  it  tends  to 
equalize  moisture  in  the  wood  and  thus  render  the  interior  more 
favorable  to  decay. 

Stains,  on  the  other  hand,  penetrate  the  wood,  although  as  a 
rule  only  a  slight  distance  from  the  surface.  In  addition,  they 
are  generally  toxic,  so  that  fungi  coming  in  contact  with  them 
will  be  killed.  The  composition  of  stains  varies  greatly  but  they 
commonly  have  a  base  of  creosote  either  from  coal-,  oil-,  or  wood- 
tars,  to  which  is  added  a  vegetable  or  mineral  oil  to  act  as  a 
body  for  the  pigment  they  carry.  Best  results  with  stains  are 
secured  by  applying  them  only  to  thoroughly  air-dry  wood,  and 
whenever  possible  heating  them  slightly  so  that  greater  pene- 
trating power  is  obtained.  As  a  rule,  stains  are  better  pre- 
servatives of  wood  than  paints,  and  their  use,  particularly 
for  dwellings,  has  become  very  popular  of  late. 


CH4PTER  VII 

THE    CONSTRUCTION    AND     OPERATION    OF    WOOD 
PRESERVING  PLANTS 

In  Chapter  V  we  described  the  relative  merits  of  the  open- 
tank  and  pressure  plants  and  the  general  features  of  their  opera- 
tion dependent  upon  the  particular  process  selected.  In  this 
chapter  we  will  describe  the  construction  of  the  plants,  the 
effect  of  the  various  mechanical  manipulations  used  in  them, 
such  as  pressure,  vacuum,  etc.,  and  the  cost  of  building  the 
plants. 

Open-tank  Plants. — Several  types  of  open-tank  plants  have 
been  constructed.  Perhaps  the  simplest  consists  in  fitting  an 
iron  pipe  3  or  4  inches  in  diameter,  blind  at  one  end,  into  a 
wooden  or  iron  barrel.  A  fire  is  then  built  around  the  pipe, 
which  thus  heats  the  oil  in  the  barrel.  With  wooden  barrels 
trouble  is  likely  to  be  experienced  in  maintaining  tight  joints. 
If  desired  2  barrels  can  be  joined  together  with  one  piece 
of  pipe  about  8  feet  long,  and  the  capacity  of  the  plant  thus 
doubled.  Plants  of  this  kind  cost  less  than  $5  each.  (See  Plate 
VII,  Fig.  A.) 

Another  simple  method  consists  in  building  a  fire  directly 
under  an  iron  barrel  or  tank  which  is  mounted  upon  stones  to 
form  a  proper  foundation  and  fire  box.  More  effective  results 
are  secured  by  walling  the  vessel  with  brick  or  stone,  thus 
allowing  the  heat  to  pass  around  the  sides  as  well  as  the  bottom. 
The  draft  can  also  be  controlled  through  a  small  pipe.  (See  Plate 
VII,  Fig.  B.)  Plants  of  this  type  cost  from  $10  to  $25  each. 

In  the  types  just  described,  it  is  difficult  to  control  the  in- 
tensity of  the  heat.  Better  results  can  be  secured  if  steam  is 
employed,  this  being  passed  through  coils  in  the  bottom  of  the 
tank.  Plate  VII,  Fig.  C,  shows  such  an  apparatus  in  which  the 
steam  is  supplied  by  a  traction  engine.  In  order  to  cheapen 
the  cost  of  the  tank,  sheet  or  galvanized  iron  reinforced  in  a 
wooden  frame  may  be  used  in  place  of  heavier  metal.  If  desired 
a  second  tank  capable  of  submerging  the  entire  timber  in  cool 

89 


90          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

preservative  can  be  used  and  the  capacity  of  the  plant  thereby 
increased.  Such  a  plant  including  piping  costs  about  $50. 

A  still  more  elaborate  type  consists  in  building  a  large  rec- 
tangular or  cylindrical  open  tank  of  1/4-inch  or  5/16-inch  iron 
of  various  dimensions  depending  upon  the  size  of  the  material  to 
be  treated,  and  pumping  the  preservative  into  it  after  the  wood  has 
been  placed  in  position.  This  necessitates,  in  addition  to  the 
treating  tank,  a  good  force  pump,  boiler,  and  auxiliary  tanks  to 
hold  the  preservative.  Plants  of  this  kind  are  well  adapted  for 
treating  larger  quantities  of  timber  than  would  ordinarily  be  the 
case  in  the  plants  described  above,  or  heavier  timbers  such  as 
poles.  Their  cost  varies,  of  course,  with  their  size,  but  will  range 
from  about  $2000  to  $6000.  One  similar  to  that  shown  in  Plate 
VI,  Fig.  C,  cost  $2500  complete. 

All  the  plants  above  described  are  aimed  to  heat  only  a  portion 
of  the  timber,  although  the  entire  stock  can  in  some  cases  be 
submerged  in  the  preservative  should  this  be  considered  neces- 
sary. Another  type  of  plant  for  treating  comparatively  large 
quantities  of  small  timber  such  as  ties  and  poles  consists  in 
passing  them  through  the  hot  preservative  by  means  of  an 
endless  chain,  the  length  of  time  they  are  in  the  preservative  being 
controlled  by  the  speed  of  the  chain.  Such  a  plant  is  shown  in 
Plate  VII,  Fig.  D,  and  has  been  used  with  satisfactory  results  by 
a  traction  company  in  New  Jersey.  It  cost  about  $1600  and 
has  a  capacity  of  about  1200  ties  per  10-hour  day.  Because 
of  the  large  surface  exposed,  only  those  preservatives  which 
volatilize  at  high  temperatures  should  be  used  if  most  economic 
results  are  to  be  secured.  Treatments  in  plants  of  this  kind  are 
really  nothing  but  prolonged  dipping  reatments  and  in  this  respect 
differ  from  the  Giussani  process,  which  submerges  the  wood  in  a 
subsequent  bath  of  cool  preservative  by  passing  it  through  a 
second  tank. 

Pressure  Plants. — Considerable  quantities  of  timber  are  most 
efficiently  handled  in  pressure  plants,  which  fact  accounts  for  the 
large  number  now  operating  in  this  and  foreign  countries.  (See 
Plate  VI,  Fig.  D  and  Plate  VIII,  Fig.  A.)  The  essential  features 
in  all  plants  operating  on  this  basis  are  quite  similar,  although 
the  details  of  construction  and  operation  vary  through  wide 
limits,  these  depending  upon  the  opinions  and  experience 
of  their  builders  and  the  class  of  work  the  plant  is  to  handle. 
In  general,  the  following  units  are  characteristic  of  all  pres- 


PLATE  VII 


FIG.  A. — A  post  treating  plant  made  of  two  barrels  and  an  iron  pipe.     (For- 
est Service  photo.) 


FIG.  B. — An  open  tank  post  treating  plant — California.     (Forest  Service 

photo.) 

(Facing  poge  90.) 


PLATE  VII 


FIG.  C. — An  open  tank  post  treating  plant.  Note  heat  is  furnished  by 
steam  from  threshing  engine.  Small  cylindrical  tank  is  for  butt  treating  in 
a  hot  bath;  rectangular  tank  is  for  a  cold  bath.  (Forest  Service  photo.) 


FIG.  D. — Open  tank  wood  preserving  plant  for  ties.  The  ties  are  carried 
through  the  plant  on  an  endless  chain.  (Photo  through  courtesy  of  the 
Public  Service  Corp.,  Newark,  N.  J.) 


OPERATION  OF  WOOD  PRESERVING  PLANTS 


91 


sure  plants:  (1)  A  retort  house,  (2)  a  pump  house  or 
room,  (3)  a  boiler  house,  (4)  a  machine  shop  or  room  and  (5)  a 
yard  for  storing,  loading,  and  handling  the  timber.  Some  plants 
are  also  equipped  with  a  sawmill  for  framing  the  timber  prior  to 
its  injection  with  preservatives.  The  arrangement  of  these 
units  in  a  typical  'plant  is  shown  in  Fig.  10.  Variations,  of 
course,  occur,  especially  if  the  plant  is  to  operate  a  special  process, 
or  only  on  a  given  kind  of  timber.  Furthermore,  the  cylinders 
may  vary  in  number  from  1  to  9  or  more,  in  which  case  a  different 
arrangement  of  the  units  would  be  made. 


Plan  Showing  Yard  Layout 


To  City 


FIG.  10. — Plan  showing  layout  of  a  typical  wood  preserving  plant.     (Draw- 
ing through  courtesy  of  the  Ry.  Eng.  and  M.  of  Way.) 

The  Retort  House. — The  retort  house  is  built  primarily  to  cover 
and  protect  the  treating  cylinders  or  retorts.  In  best  con- 
struction it  is  made  of  steel,  brick,  or  re- enforced  concrete,  al- 
though a  wooden  structure  may  be  used  if  minimum  cost  is 
desired.  To  guard  against  loss  of  preservative  due  to  leaks, 
or  accident,  the  floor  is  sometimes  made  of  solid  concrete  with 
appropriate  drains  to  a  sewer  or  underground  tank,  and  de- 
pressed so  that  the  level  of  the  rails  in  the  retorts  will  be  the  same 
as  that  of  the  outside  tracks.  It  is  well  to  so  construct  the  build- 
ing that  a  free  ventilation  can  be  obtained  to  carry  off  the  vapors 
which  frequently  arise  during  the  operation  and  to  keep  the 
temperature  in  the  house  from  becoming  oppressive  to  the 
workmen. 

Retorts  (or  Cylinders). — These  are  invariably  built  of  steel 
and  are  cylindrical  shells  mounted  horizontally  upon  concrete 
piers.  Their  diameter  varies  from  about  6  to  9  feet,  and  length 
from  about  50  to  180  feet.  A  good  size  is  7  feet  X  132  feet. 
The  7-foot  diameter  enables  a  more  economic  utilization  of  space 
in  the  cylinder  than  a  smaller  diameter  and  is  not  too  large  to 


92          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

make  the  handling  of  the  cylinder  cars  expensive  and  clumsy. 
The  same  reasoning  applies  to  a  length  of  132  feet  or  thereabouts. 
The  thickness  of  the  metal  in  the  retorts  varies  from  about  5/16 
to  1  inch.  Good  practice  is  to  use  metal  of  such  thickness  that 
working  pressures  of  150  to  175  pounds  can  be  safely  used.  In 
some  cases  lower  pressures  of  100  to  125  pounds  give  satisfaction. 
The  plates  of  which  the  retorts  are  made  are  riveted  with  either 
butt  or  lap  j  oints.  For  high  pressures  the  former  is  the  more  satis- 
factory. In  order  to  completely  drain  the  retorts  a  slight  pitch  is 
given  them.  It  is  very  important  to  have  the  retorts  mounted 
upon  firm  piers,  or  trouble  from  buckling  is  likely  to  occur.  If 
the  plant  is  built  on  marshy  ground  the  piers  should  be  made 
wide  at  the  base  and  close  together  or  mounted  on  piles.  The 
retort  is  perforated  to  admit  pipes,  gauges  and  thermometers,  and 
often  has  a  small  dome  riveted  on  the  top  and  in  the  middle  to 
act  as  an  expansion  chamber  for  the  contained  air  and  oil. 

Retort  Thermometer. — The  manner  of  placing  the  retort 
thermometer  is  very  important  or  incorrect  readings  of  tem- 
perature will  result.  The  bulb  of  the  thermometer  should  not 
be  too  close  to  the  shell  of  the  retort  but  should  be  at  least  2 
inches  from  it.  The  thermometer  preferably  should  be  inserted 
near  the  middle  of  the  retort  and  half  way  up.  In  order  to  be 
sure  of  the  reading  a  pet  cock  should  be  inserted  in  the  ther- 
mometer plate  and  some  oil  drawn  off  during  the  treatment. 
In  addition  to  the  direct-reading  thermometer,  recording  ther- 
mometers are  also  highly  desirable,  as  they  give  a  complete  record 
of  temperature  during  the  entire  treatment  and  enable  the 
manager  to  get  an  accurate  check  on  his  men.  Care  should  be 
exercised  to  see  that  the  thermometer  is  properly  calibrated  and 
guarded  against  the  men  tampering  with  it.  By  ascertaining  the 
temperature  at  various  points  in  the  retort  (by  means  of  a 
maximum  and  minimum  thermometer)  the  thermometer  inserted 
in  the  shell  can  be  calibrated  to  give  the  average  reading  in  the 
cylinder. 

Retort  Gauges. — These  are  inserted  in  the  retort  to  record  the 
pressures  in  it,  whether  above  or  below  atmospheric.  They  may 
be  inserted  at  any  convenient  point  in  the  top  of  the  shell.  If 
direct  reading,  the  gauges  should  be  protected  from  injury  by 
preservative  by  means  of  a  water  seal  or  diaphragm.  The 
author's  experience  with  combination  pressure  and  vacuum 
gauges  has  not  been  satisfactory  and  it  is  believed  separate  gauges 


FIG.  A. — Small  wood  preserving  plant  designed  by  the  U.  S.  Forest 
Service  in  co-operation  with  the  Louisiana  Creosoting  Co.  (Forest  Service 
photo.) 


FIG.   B. — View  through  a  large  treating  cylinder.     Note  guard  rails,  steam 
coils    and   track.     International   Creosoting   and   Construction   Company. 

(Facing  page  92.) 


PLATE  VIII 


FIG.  C. — Spider  door  with  independent  sockets.     (Photo,  through  courtesy 
of  the  Allis  Chalmers  Mfg.  Co.) 


FIG.  D. — Spider  door  with  continuous   socket   support.     (Photo  through 
courtesy  of  the  Allis  Chalmers  Mfg.  Co.) 


FIG.  E. — Construction  of  a  cast  steel  door.     (Photo  through  courtesy  of 
the  Allis  Chalmers  Mfg.  Co.) 


OPERATION  OF  WOOD  PRESERVING  PLANTS  93 

give  better  results.  Self-recording  gauges  are  highly  recom- 
mended. 

Anchors  and  "Turtles."— As  the  temperature  of  the  retort 
varies  considerably,  it  is  necessary  to  anchor  the  retort  and  also 
allow  for  its  expansion  and  contraction.  Anchorage  can  best  be 
made  at  the  middle.  There  are  several  methods  of  doing  this 
but  embedding  a  channel  or  angle  iron  riveted  to  the  retort 
in  a  concrete  pier  or  "tie  rods"  in  two  piers  prove  satisfactory. 
In  some  plants  the  retorts  rest  in  cast-iron  saddles  or  "turtles," 
which  are  permitted  to  slide  back  and  forth  over  plates  embedded 
in  the  piers,  thus  providing  for  expansion.  In  other  cases  the 
turtles  are  made  of  wood.  Although  steel  rollers  are  sometimes 
used  to  permit  a  freer  movement  of  the  "turtles,"  they  are  not 
necessary,  as  equally  satisfactory  results  can  be  obtained  by 
simply  permitting  the  expansion  and  contraction  to  take  place  over 
flat  surfaces. 

Retort  Coils. — Steam  coils  placed  in  the  bottom  of  the  retort, 
generally  over  its  entire  length  in  order  to  heat  the  preservative, 
are  a  source  of  constant  expense  and  trouble  unless  they  are 
properly  laid,  as  they  dilute  the  preservative  with  steam  and  cause 
leakage  of  the  preservative.  (See  Plate  VIII,  Fig.  B.)  The  im- 
portance of  first- class  construction  in  these  coils  cannot  be  over- 
emphasized. A  few  plants  omit  the  coils  but  as  a  general  rule 
they  are  necessary  for  best  results.  Common  practice  consists 
in  screwing  extra  heavy  1  1/4  to  2-inch  pipes  into  extra  heavy 
return  bends  or  headers.  If  this  is  done  only  sharp  threads  should 
be  used  and  no  white  lead  or  any  similar  material  should  be 
permitted  in  order  to  makethe  joints  tight.  Two  schemes  which 
appear  meritorious  are  to  use  cast-iron  radiators  in  place  of  coils, 
these  being  coupled  in  series,  or  to  place  one  steam  pipe  in- 
side another,  leaving  one  end  free  so  that  it  can  expand  and 
contract  at  will.  This  latter  device  has  been  found  very  satis- 
factory in  practice.  In  order  to  protect  the  coils  from  possible 
injury  due  to  derailment  and  from  dirt  off  the  timber,  per- 
forated steel  plates  are  frequently  laid  over  them. 

Guard  Rails. — When  the  cylinder  cars  loaded  with  wood  are  run 
into  the  treating  retorts,  the  tendency  is  for  them  to  float  off  the 
track  after  the  perservative  is  admitted.  This  is  because  the 
buoyant  force  exerted  by  the  wood  is  greater  than  the  dead  weight 
of  the  cars.  To  overcome  the  possibility  of  such  trouble,  guard 
rails  are  generally  used.  Three  types  of  such  guard  rails  are  in 


94          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

use.  In  one  an  angle  iron  is  bolted  to  the  seats  riveted  to  the 
shell  of  the  cylinder.  The  car  with  its  load  can  float  partially  off 
the  tract  equal  to  the  distance  between  the  top  of  the  retort  and 
the  top  of  the  iron  bale  or  hoop  fastened  to  the  car — a  space  usually 
of  1  1/2  to  3  inches.  As  the  preservative  is  run  from  the  cylinder 
the  car  gradually  settles  into  position  on  the  track. 

In  the  other  two  types  a  projecting  flange  is  generally  riveted 
to  the  cylinder  car,  which  slides  under  the  guard  rail  and  thus 
prevents  the  car  from  floating,  the  only  difference  in  the  two 
types  being  that  in  one  the  projecting  flange  is  riveted  on  the 
bottom  of  the  car,  while  in  the  other  it  is  on  top  of  the  frame. 

Retort  Doors. — These  may  be  fastened  on  one  or  both  ends  of  the 
treating  cylinder,  depending  largely  upon  the  ease  with  which 
the  timber  can  be  handled  in  the  yard.  Retorts  with  but  one 
door  are  entirely  satisfactory  and  in  the  author's  opinion  are 
preferable  to  retorts  with  doors  at  both  ends.  When  one  door  is 
used  the  other  end  of  the  cylinder  is  closed  with  a  dished  head, 
thus  saving  extra  expense  and  often  trouble.  Retort  doors  are 
always  fitted  to  cast-iron  or  steel  rims  or  " collars"  riveted  to  the 
shell  of  the  cylinder.  These  collars  are  machined  with  a  dove- 
tailed groove  to  hold  a  gasket  against  which  the  " tongue"  on  the 
door  can  press.  Asbestos  rope  pounded  into  this  groove  and  its 
surface  kept  well  lubricated  with  graphite  and  oil  makes  a  very 
satisfactory  packing. 

There  are  several  types  of  doors  but  they  may  be  classed 
.into  two  groups,  " spider  doors"  and  "bolt  doors."  The  former 
enable  the  cylinder  to  be  opened  and  locked  easily  and  quickly, 
and  for  this  reason  are  preferred  by  some.  They  are,  however, 
more  expensive  than  bolt  doors  and  are  more  liable  to  get  out  of 
adjustment  and  cause  leaks.  Two  kinds  of  spider  doors  are 
generally  used.  The  one  shown  in  Plate  VIII,  Fig.  C,  has  a 
center  screw  and  lever  nut  arranged  so  that  each  lever  has  an 
independent  connection  to  the  frame.  The  type  shown  in  Plate 
VIII,  Fig.  D,  is  stronger  and  better  constructed  and  so  arranged 
that  the  levers  are  connected  to  the  frame  by  a  continuous- 
flange  ring.  Both  of  these  types  swing  on  hinges. 

Most  treating  plants  now  use  some  form  of  bolt  door,  as  the 
small  time  of  opening  and  closing  is  not  a  very  important  factor, 
their  cost  is  low,  and  their  construction  simple  and  efficient. 
There  are  several  types  of  bolt  doors  and  several  methods  of 
arranging  the  bolts.  A  good  type  is  one  constructed  of  solid 


OPERATION  OF  WOOD  PRESERVING  PLANTS  95 

cast  steel,  with  independent  Tee-bolts  fastened  to  the  cylinder 
and  swinging  on  hinges  without  a  wheel  support.  This  is 
shown  in  Plate  VIII,  Fig.  E...  Doors  are  sometimes  constructed 
of  a  cast-steel  rim  to  which  is  riveted  to  a  dished-steel  plate. 
Such  doors  are  light  in  wei|fht  but  not  as  strong  as  those  of 
solid  cast  steel.  (See  Plate  IX,  Figs.  A  and  B.)  In  some  plants  the 
bolts  are  not  mounted  to  the  cylinder  but  simply  rest  in  slots 
so  they  can  be  removed  when  not  in  use.  This  is  the  cheapest 
construction  but  not  as  good  as  where  the  bolts  are  fastened  and 
hence  always  in  position  ready  for  use.  Bolts  with  an  "eye" 
in  place  of  a  "Tee"  are  also  used,  being  fastened  to  a  ring  which 
passes  through  the  eye,  which  is  in  turn  tapped  to  the  collar  on 
the  cylinder.  This  construction  is  very  satisfactory  but  has  an 
objection  in  that  if  one  bolt  becomes  damaged  it  is  necessary  to 
remove  all  those  fastened  to  the  portion  of  the  ring  on  which  it 
swings  in  order  to  make  repairs.  However,  as  such  damage 
occurs  but  seldom  and  as  this  construction  is  cheaper  than  the 
independent  Tee-bolts,  it  has  very  much  merit  in  its  favor. 

It  is  very  important  to  properly  imbed  the  curved  iron  plate 
or  rail  upon  which  the  door  wheel  rolls  or  the  door  will  either 
jam  or  not  rest  on  the  wheel.  Furthermore,  improper  founda- 
tions will  throw  the  cylinder  out  of  alignment  and  render  the 
wheel  useless. 

In  order  to  avoid  hinges,  doors  are  sometimes  cast  without  them, 
as  is  shown  in  Plate  XI,  Fig.  C.  In  this  case  they  are  supported 
on  a  small  derrick  or  overhead  track  so  they  can  be  swung  or 
run  out  of  the  way  during  the  transfer  of  the  cars.  Further- 
more, they  render  it  unnecessary  to  entirely  remove  the  nut 
as  is  done  on  some  of  the  bolts  near  the  hinge.  However,  by 
proper  design  this  objection  can  be  remedied  on  the  hinged 
door. 

Retort  Lagging. — Practice  in  regard  to  lagging  or  covering 
the  retorts  to  prevent  heat  losses  due  to  radiation  varies  widely. 
In  northern  plants  where  fuel  is  high  and  outside  temperature 
at  times  very  low,  several  plants  have  covered  their  retorts  and 
tanks  and  secured  very  good  results.  The  chief  objection  to 
covering  retorts  is  the  expense  and  trouble  in  case  of  cylinder 
leaks.  It  is  common  practice,  however,  to  lag  all  steam  pipes. 
Most  plants  use  exhaust  steam  to  heat  these  various  tanks  and 
consider  the  lagging  of  the  retort  unnecessary.  It  is  the  author's 
opinion  that  lagging  is  desirable  and  if  properly  applied  will  more 


96          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

than  pay  for  itself  in  a  few  years.  Mr.  R.  W.  Yarborough  con- 
tributed an  interesting  paper  on  this  subject  at  the  1911  con- 
vention of  the  Wood  Preservers'  Association.  Mr.  Yarborough 
roughly  estimated  that  about  2,000,000  B.T.Us,  were  lost  per 
hour  in  operating  a  retort  7  feet  X  132  feet,  which  is  equivalent  to 
the  consumption  of  about  187  pounds  of  coal.  With  coal  at  $3 
per  ton,  this  represents  a  loss  of  about  30  cents  per  hour,  or  $2.40 
per  8-hour  day.  It  costs  about  $300  to  $1200  to  cover  a 
7  foot  X  132  foot  retort,  depending  upon  the  kind  of  lagging  used. 
Most  any  fibrous  material  which  is  a  poor  heat  conductor  can 
be  employed.  Cheap  coverings  can  be  made  according  to  the 
following:  (1)  Sawdust  and  starch  re-enforced  with  poultry  wire, 
(2)  cotton  seed  hulls,  (3)  mixture  in  equal  parts  of  lime,  sawdust, 
and  asbestos,  (4)  sawdust,  tar  felt,  and  wood  slats. 

The  Pump  House  or  Room. — It  is  highiy  desirable  to  have  the 
pumping  machinery  as  close  to  the  retorts  as  possible,  as  this 
avoids  unnecessary  piping  and  renders  the  operation  more  accur- 
ate and  less  troublesome.  (See  Plate  IX,  Fig.  D.)  In  best  practice 
this  is  accomplished  by  either  building  the  pump  house  adjoining 
the  retort  house  or  placing  the  machinery  in  the  retort  house  and 
separating  it  from  the  retorts  by  means  of  a  fire  wall  or  partition. 
Fumes  arising  from  the  cylinders  are  thus  confined  to  the  retort 
house.  In  the  pump  ho/use  are  installed  the  force  pumps  for 
moving  the  preservatives,  vacuum  pumps,  compressed-air 
pumps,  fire  pumps,  and  at  times  electrical  equipment  in  case  the 
plant  is  to  operate  at  night.  Gauges  for  recording  temperature, 
pressure,  and  vacuum  in  the  retorts  are  also  frequently  insjftlled 
here,  as  well  as  the  devices  for  measuring  the  absorpti^rand 
consumption  of  the  preservative  in  the  retorts  and  measuring 
tanks.  The  arrangement  of  this  apparatus  is  one  of  the  most 
important  features  in  designing  a  wood  preserving  plant.  It  is 
very  essential  to  use  only  high-grade  machinery  and  then,  if 
funds  permit,  provide  for  duplicate  units.  Cheap  pumps  and 
rigid  units  always  result  in  troublesome  delays  and  repairs,  mak- 
ing good  work  almost  an  impossibility.  Machinery  made  by 
any  high-grade  concern  can,  however,  be  used,  its  selection  being 
largely  a  matter  of  personal  taste.  Rubber  gaskets  should  not 
be  permitted  if  they  are  likely  to  come  in  contact  with  creosote. 
Likewise,  if  zinc  chloride  is  to  be  used  the  pumping  parts  should 
be  so  constructed  that  they  will  not  be  corroded  too  rapidly 
and  hence  cause  the  pumps  to  work  unsatisfactorily.  It  is  es- 


PLATE  IX 


FIG.  A. — The  construction  of  the  collar  and  door  in  a  pressure  cylinder. 
Note  cylinder  track  and  guard  rails.     (Photo  courtesy  of  the  Allis  Chalmers 

Co.) 


FIG.  B. — Construction  of  a  door  with  cast  steel  rim. and  dished  plate  steel 
head.     (Photo,  through  courtesy  of  the  Allis  Chalmers  Mfg.  Co.) 

(Facing  page  96.) 


PLATE  IX 


FIG.  C. — Cylinder  doors  without  hinges.     Norfolk  Creosoting  Company. 
(Forest  Service  photo.) 


FIG.  D. — Pump  room  C.  B.  &  Q.  R.  R.  treating  plant, 
gauges  and  control  valves. 


Note  arrangement 


OPERATION  OF  WOOD  PRESERVING  PLANTS  97 

sential  also  to  have  pumps  of  such  design  that  the  packing  and 
working  parts  can  be  easily  inspected  and  replaced.  Either 
wet  or  dry  vacuum  pumps  may  be  used.  If  the  latter,  a  surface 
condenser  will  be  fqund  advantageous.  Some  plants  have  done 
away  entirely  with  force  pumps  in  moving  the  preservative  and 
applying  pressure  in  the  retorts  by  using  compressed  air.  The 
author's  experience  with  such  equipment  has  shown  it  to  be 
highly  satisfactory,  as  it  is  quick,  efficient,  and  cleans  the  pipes 
thoroughly.  Care  should  be  taken,  however,  to  prevent  an 
emulsifying  of  the  oil,  especially  if  it  contains  much  water.  In 
fact,  it  is  good  policy  to  so  design  the  plant  that  the  oil  can  be 
transferred  with  a  minimum  of  agitation. 

According  to  Mr.  F.  J.  Angier,  the  advantages  of  the  air- 
pumping  system  over  the  hydraulic  system  are:1 

"Only  one  tank  is  required  for  each  retort,  that  tank  serving  in  the 
triple  capacity  of  pressure  tank,  measuring  tank,  and  drain  tank. 

One  air  pump  is  ample  for  three  retorts,  while  one  hydraulic  pump  is 
required  for  each  retort. 

The  maintenance  of  one  air  pump  is  much  less  than  three  hydrau- 
lic pumps,  and  is  decidedly  cleaner.  The  air  pump  requires  less  at- 
tention, and  lessens  the  cost  of  packing,  lubricants,  valves,  valve  seats, 
plungers,  etc. 

An  air  pump  is  a  necessity  in  plants  using  hydraulic  pumps  for  blowing 
back  solution,  unless  those  plants  are  equipped  with  expensive  under- 
ground receiving  tanks.  In  the  latter  case  an  air  pump  can  be  dispensed 
with  in  lieu  of  a  large  oil  pump  for  pumping  solution  back  into  the  work- 
ing tank.  The  underground  receiving  tank  is  more  expensive  in  opera- 
tion than  the  air  pump,  and  no  doubt  this  is  the  reason  why  so  few  plants 
are  thus  equipped. 

One  air  pump  can  be  operated  on  two  or  more  retorts  at  the  same  time 
without  deranging  the  gauge  readings.  This  is  not  practicable  with 
hydraulic  pumps. 

Experience  has  taught  us  that  it  is  practically  impossible  to  maintain  a 
steady  and  constant  pressure  on  a  charge  of  timber  with  a  hydraulic 
pump,  even  though  it  is  equipped  with  relief  valves,  while  with  the  air 
pump  this  is  easily  accomplished. 

The  amount  of  steam  required  to  operate  one  air  pump  is  not  more 
than  would  be  required  to  operate  three  hydraulic  pumps,  but  as 
the  exhaust  steam  is  used  for  heating  purposes,  this  feature  is  not  so 
important. 

The  initial  cost  of  installing  the  air-pump  system  is  a  trifle  more  than 

1  F.  J.  Angier,  Proceedings  American  Wood  Preservers'  Ass'n.,  1914. 

7 


98          THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

for  the  hydraulic  pump  system,  but  the  maintenance  is  less,  and  in  the 
long  run  air  is  more  economical.  The  following  statement  will  give  some 
idea  of  the  relative  first  cost,  which  may  vary  one  way  or  the  other, 
depending  on  local  conditions: 

COST  OF  AIR-PUMP  SYSTEM 
One    air   pump    (capacity   8   cubic   feet   of   compressed   air   per 

minute  at  175  pounds  gauge  pressure) $1200. 00 

Three  pressure-measuring-drain  tanks 2000 . 00 

Piping,  valves,  etc.  (estimated) 400. 00 


Total  cost  of  airnydraulic-pump  system $3600 . 00 

COST  OF  HYDRAULIC  PUMP  SYSTEM 

Three  hydraulic  pumps $1000 . 00 

Three  measuring  tanks 900 . 00 

Two  drain  tanks    400. 00 

One  low-pressure  air  pump 500 . 00 

Piping,  valves,  etc.  (estimated) 600 . 00 


Total  cost  of  hydraulic-pump  system $3400 . 00 

With  hydraulic  pumps  there  is  more  machinery  to  care  for,  more 
tanks  to  look  after,  and  more  piping  and  valves  to  maintain.  There  is 
also  more  work  for  the  engineer,  and  unless  everything  is  compactly 
arranged  the  engineer  will  require  an  assistant.  With  the  air  pump  one 
man  can  easily  look  after  the  entire  operation  with  greater  satisfaction 
and  with  better  results." 

The  Machine  Shop  or  Room. — This  may  be  an  independent 
building  or  a  room  adjoining  the  retort  house,  but  in  either  case  is 
a  very  important  element  in  a  pressure  preserving  plant,  espe- 
cially if  the  plant  is  remotely  situated.  In  addition  to  hammers, 
chisels,  wrenches,  etc.,  it  is  very  desirable  to  have  a  good  forge, 
especially  for  repairing  cylinder  cars.  If  the  plant  is  large  a  lathe 
will  also  be  found  handy.  Too  much  attention  cannot  be  paid  to 
a  good  pipe-fitting  outfit,  and  only  clean,  sharp  dies  should  be 
permitted  about  the  plant. 

The  Boiler  House. — As  a  precaution  against  fire,  the  boiler 
house  should  be  a  separate  building  situated  some  distance  from 
the  treating  plant  proper.  There  is  nothing  novel  about  the 
construction  of  the  boiler  house.  A  common  mistake,  however,  is 
to  underestimate  boiler  capacity,  especially  where  steaming  is 
practised  and  low  temperatures  are  encountered.  A  good  ratio 
is  about  160  H.P.  to  a  cylinder  7  feet  in  diameter  X  132  feet  in 
length  with  a  working  pressure  of  125  pounds. 


OPERATION  OF  WOOD  PRESERVING  PLANTS  99 

Yard. — The  yard  arrangement  is  one  of  the  most  important 
features  of  a  wood  preserving  plant.  (See  Plate X,  Fig.  A.)  To 
have  the  yard  designed  jri'  a  flexible  manner  so  any  point  can  be 
easily  reached  without  unnecessary  distance,  to  economize  in  track 
equipment,  to  allow  proper  storage  for  the  timber,  and  ready 
means  of  loading  and  unloading  it  is  not  a  problem  easy  of  solu- 
tion. Many  yards  are  poorly  designed,  resulting  in  an  unnec- 
essary initial  expenditure  and  excessive  operating  costs.  While 
the  yard  layout  will  vary  considerably  depending  upon  the  re- 
quirements peculiar  to  each  plant,  certain  general  essentials 
applicable  to  all  yards  can  be  given. 

In  the  first  place,  the  yard  should  be  level,  well  drained,  free 
from  rank  vegetation,  and  if  possible  covered  with  cinders.  The 
timber  should  be  piled  off  the  ground  at  least  8  inches,  preferably  on 
creosoted  stringers,  with  sufficient  space  between  the  piles  to  allow 
a  free  circulation  of  air  and  ready  inspection.  No  decayed  wood 
about  the  yard  should  be  tolerated. 

The  track  should  be  well  constructed,  with  good  bearing  for 
each  tie,  properly  spaced,  in  perfect  alignment,  and  even  grades. 
The  rail  should  not  be  too  light  but  should  run  60  pounds  or  over. 
To  use  a  very  light  rail  or  old  rail  badly  worn  or  pitted  is  poor 
economy.  So  far  as  possible  the  track  should  be  straight  and 
sharp  curves  avoided.  A  good  working  distance  between  tracks, 
center  to  center,  is  50  to  70  feet.  If  the  plant  is  to  handle 
several  forms  of  timber,  especially  piling,  poles,  and  long  dimen- 
sion stock,  the  use  of  3-rail  track  for  standard  and  narrow 
gauge  is  satisfactory  and  economical  but  liable  to  cause  delays. 
If  only  ties  are  to  be  treated,  a  narrow  gauge  in  the  yard  proper 
is  sufficient,  standard  gauge  being  used  only  to  tap  the  main 
centers  of  distribution.  The  number  of  frogs  and  crossovers 
should  be  kept  to  a  minimum,  but  should  allow  sufficient  flex- 
ibility in  moving  trams  or  cars.  The  use  of  a  transfer  table  has 
been  suggested  by  Mr.  W.  F.  Goltra  in  order  to  keep  the  number 
of  switches  to  a  minimum.  There  appears  much  merit  in  this 
scheme.  A  yard  arrangment  for  a  tie  plant  is  shown  in  Fig.  10. 

Loading  Dock. — If  the  plant  is  to  handle  larg§  numbers  of  ties, 
a  loading  dock  will  be  found  very  useful,  especially  if  the  plant  re- 
ceives mostly  flat  cars  or  gondolas  and  the  ties  are  loaded  by 
hand.  The  dimensions  of  the  loading  dock  will  vary,  of  course, 
with  the  size  of  the  plant,  but  it  should  have  an  elevation  at 
least  equal  to  the  height  of  the  floor  in  freight  cars.  A  loading 


100        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

dock  for  ties  is  shown  in  Plate  X,  Fig.  B.  The  loading  dock 
enables  the  foreman  to  easily  keep  his  workmen  in  view. 

Methods  of  Transferring  Material  in  the  Yard. — Practice 
varies  and  opinions  differ  concerning  the  best  method  of  handling 
timber  in  the  yard.  The  tram  or  cylinder  cars  are  moved  in  four 
ways:  by  cables,  dummy  engines,  electric  locomotives,  and  by 
horses  or  mules.  For  tie  plants  where  the  yard  arrangement  can 
be  simplified,  electric  locomotives  are  very  satisfactory.  For 
general  all-around  work  the  dummy  engine  is  satisfactory,  as  it 
is  inexpensive,  flexible,  and  efficient.  If  properly  handled  it  offers 
no  unusual  fire  risk.  When  labor  is  avialable,  loading  and  un- 
loading ties  by  hand  is  still  best  practice,  especially  when  it  can 
be  done  by  piece  work.  Some  plants,  however,  use  the  locomo- 
tive crane  moving  a  whole  buggy  load  of  ties  at  a  time.  (See  Plate 
X,  Fig.  C .)  For  timbers  which  are  too  heavy  to  be  moved  by  hand 
the  author  prefers  the  locomotive  crane  to  any  other  system,  large- 
ly because  of  its  efficiency  and  flexibility.  Stationary  derricks 
operated  by  cables  are  also  satisfactory  for  heavy  timbers,  but 
have  not  the  radius  of  action  of  the  locomotive  crane.  Traveling 
cranes  are  also  used  by  some  plants  but  like  the  derrick  are  limited 
in  their  territory.  Furthermore,  unless  the  structures  on  which 
they  run  are  properly  braced  and  mounted  on  solid  foundations, 
they  will  get  out  of  alignment  and  cause  trouble.  In  a  few  treat- 
ing plants  small  canals  filled  with  water  run  through  the  yard. 
The  heavy  timbers  are  rolled  off  skids  into  these  canals  and 
floated  to  the  retort  house,  where  they  are  placed  on  the  cylinder 
cars  by  a  traveling  crane.  (See  Plate  X,  Fig.  D.)  A  few  coast  plants 
store  their  heavy  timbers  as  rafts  in  water — a  method  which  of 
courseprecludes  any  air  seasoning. 

Cylinder  Cars. — These  are  also  referred  to  as  tram  cars,  bolster 
cars,  retort  cars,  and  " buggies."  Three  general  types  are  gen- 
erally recognized:  (1)  a  tie  car  of  rigid  construction  throughout, 
(2)  a  swivel  or  bolster  car  which  has  a  pivot  bearing  to  allow  for 
long  timbers  in  rounding  curve,  and  (3)  a  block  car  for  holding  pav- 
ing blocks.  Two  of  these  types  are  shown  in  Plate  XI,  Fig.  A,  and 
Fig.  B.  There  are  two  essential  features  in  the  proper  building  of  all 
types,  which  are  often  sadly  neglected,  viz.,  a  heavy,  substantial 
construction  and  a  maximum  holding  capacity.  On  account  of 
the  severe  usage  to  which  the  cars  are  put,  they  should  be  made  very 
strong  or  they  will  soon  be  broken  or  bent  and  consigned  either  to 
the  repair  shop  or  scrap  heap.  Especial  attention  should  be  given 


PLATE  X 


FIG.  A. — Chicago  and  Northwestern  Tie  Treating 
(Photo  through  courtesy  C.  & 


Plant,  Escanaba,   Mich. 
N.  W.  R.  R..) 


FIG.  B. — Tie  treating  plant  of  the  Pennsylvania  R.  R.  Note  concrete 
loading  dock  with  empty  cylinder  cars  on  top,  also  manner  of  unloading 
and  piling  ties  for  air  seasoning.  (Photo  through  courtesy  of  the  P.  R.  R.) 

(Facing  page  100.) 


PLATE  X 


r 


FIG.  C. — Unloading  treated  ties  from  cylinder  buggies  into  gondolas 
with  a  locomotive  crane.  Port  Reading  Creosoting  Co.  (Forest  Service 
photo.) 


FIG.  D. — Overhead  electric  crane  for  loading   timber  into  cylinder  cars. 
Gulf  port  Creosoting  Co.,  Gulf  port,  Miss. 


OPERATION  OF  WOOD  PRESERVING/KtiW'SS. 


to  properly  reenforcing  the  curved  arms  soM^ey>wiU:ii6t'>be:tfel  aaidi 
jam  in  the  cylinder.  The  frame  work  should  also  be  set  low  or 
the  treating  capacity  of  the  plant  will  be  greatly  decreased.  A 
solid  iron  hoop  or  " bail"  is  preferred  to  chains,  in  order  to  hold  the 
timbers  on  the  car,\nd  no  jamming  or  pounding  of  the  bails 
should  be  tolerated.  It  is  almost  universal  practice  to  build  the 
cars  without  couplers,  the  idea  being  to  save  expense,  time  and 
space  in  the  cylinder.  Hence  the  cars  must  always  be  pushed 
and  never  pulled.  Some  plants  broke  away  from  this  practice  and 
used  couplers  on  their  cars  so  they  could  be  pulled  as  well  as 
pushed — a  scheme  which  has  been  prohibited  in  certain  states 
because  of  danger  to  workmen.  Block  cars  can  be  made  out  of 
tie  cars  by  simply  placing  on  the  tie  car  a  perforated  sheet-iron 
basket  with  hinged  doors.  In  some  cases  the  cars  are  built 
purposely  for  handling  blocks  and  so  designed  that  they  can  be 
emptied  by  lifting  them  bodily  with  a  locomotive  crane  and  turn- 
ing them  upside  down. 

A  good  feature  in  the  design  of  cylinder  cars  is  to  have  loose 
wheels  of  heavy  construction  fitted  with  roller  bearings  and  a 
fairly  wide  tread. 

Measuring,  Mixing,  Working,  and  Storage  Tanks. — A  meas- 
uring tank  is  one  used  for  measuring  the  absorption  of  pre- 
servative forced  into  the  wood.  It  is  invariably  constructed  of 
steel.  It  is  considered  good  practice  to  have  the  diameter  of  these 
tanks  as  small  as  possible  in  order  to  allow  for  an  accurate  reading 
of  the  preservative  and  to  have  them  accurately  calibrated. 
Furthermore,  they  should  be  placed  as  close  to  the  retorts  as 
proper  design  will  permit.  Some  engineers  have  carried  this 
idea  as  far  as  to  place  them  directly  over  the  retorts.  The  size 
of  the  measuring  tanks  in  relation  to  the  size  of  the  retort  varies 
greatly  in  practice.  In  some  plants  the  volume  of  the  measuring 
tanks  is  1 1/2  times  the  volume  of  the  cylinder,  in  others  it  is  less 
than  half  the  volume  of  the  cylinder.  In  most  plants  these 
tanks  are  built  to  withstand  the  pressure  due  to  only  the  head 
of  the  preservative,  and  are  elevated  upon  stationary  platforms 
so  that  the  preservative  can  flow  from  them  into  the  retorts 
by  gravity.  In  a  few  plants,  using  compressed  air,  the  meas- 
uring tanks  are  mounted  on  the  ground  and  built  to  withstand 
a  working  pressure  equal  to  that  of  the  retorts.  Another  design 
mounts  the  measuring  tanks  upon  scales  so  that  as  the  preservative 
is  pumped  out  of  them  through  flexible  connections  the  amount 


102       THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


.  forced  into  the  retorts  can  be  read  directly.  All 
float  gauges  are  in  this  case  done  away  with.  The  author  prefers 
the  two  latter  designs  of  constructing  tanks  of  this  kind. 

Mixing  tanks  are  used  for  making  solutions  of  zinc  chloride. 
A  substantial  construction  is  to  use  wood  lined  with  lead.  Con- 
centrated solutions  of  zinc  chloride  are  basic  and  will  attack 
wood.  If  tar  is  mixed  with  creosote  the  tajiks  in  which  this  is 
done  are  also  sometimes  called  "  mixing  tanks"  and  are  generally 
built  of  steel. 

Working  tanks  ace  intermediate  in  size  to  measuring  and  stor- 
age tanks  and  are  in  common  use.  They  are  not  used  to  measure 
absorption  but  to  aid  the  measuring  tanks  in  filling  the  retorts 
with  preservative.  In  other  words,  after  the  wood  has  been 
placed  in  the  retorts  and  the  doors  locked,  the  preservative  is 
run  from  the  working  tank  until  the  retort  is  filled,  after  which 
the  preservative  is  drawn  from  the  measuring  tank.  Working 
tanks  are  usually  built  of  steel  and  elevated  so  that  the  pre- 
servative can  run  from  them  into  the  retorts  by  gravity.  If  zinc 
chloride  is  used,  the  tanks  are  frequently  built  of  wood,  as  weak 
solutions  of  zinc  chloride  will  attack  steel.  In  some  plants 
working  tanks  are  not  used,  in  which  case  the  measuring  tanks 
are  made  with  larger  capacity.  Working  tanks  may  have  from 
about  1  to  3  times  the  capacity  of  the  retorts. 

Storage  tanks,  as  the  name  implies,  are  used  to  store  the 
preservative.  There  is  no  agreement  as  to  size,  this  depending 
upon  the  requirements  of  each  plant.  They  are  generally  located 
some  distance  from  the  plant  proper  as  a  matter  of  safety.  It  is 
well  to  have  the  storage  tanks  at  least  sufficiently  large  to  allow 
for  a  month's  supply  when  operating  at  full  capacity.  On  account 
of  their  large  size,  storage  tanks  are  frequently  built  without  a 
roof,  evaporation  of  oil  being  retarded  by  means  of  a  water  seal. 
Generally  the  measuring  and  working  tanks  are  covered. 

Some  plants  are  equipped  with  receiving  tanks,  which  are 
buried  below  ground  so  that  the  excess  preservative  in  the  retorts 
can  be  drained  into  them,  after  which  it  is  pumped  back  into  the 
working  or  measuring  tanks.  This  enables  a  quick  emptying  of 
the  cylinders.  When  the  excess  preservative  is  pumped  or 
blown  back  from  the  cylinders,  these  tanks  are  unnecessaiy. 

Because  creosote  congeals  at  low  temperatures,  all  of  the 
tanks  described  are  generally  fitted  with  steam  coils  through 
which  exhaust  or  live  steam  may  be  passed.  Traps  should  be 


PLATE  XI 


FIG.  A. — Bolster  Car.     Used  for  long  timbers.     (Photo  through  courtesy 
of  the  Allis  Chalmers  Mfg.  Co.) 


FIG.  B. — A   tie    car.     (Photo    through    courtesy   of   the    Allis    Chalmers 

Mfg.  Co.) 

(Facing  page  102.) 


PLATE  XI 


FIG.  C. — Mercury  gauge  for  measuring  the  preservative  in  the  measuring 
tank.  Baltimore  &  Ohio  R.  R.  Tie  Plant.  (Photo  through  courtesy  of 
the  B.  &O.  R.  R.) 


FIG.  D. — Wood  Block  treating  plant  of  the  Chicago  Creosoting  Co.,  Terre 
Haute,  Ind.  Note  vertical  cylinders.  (Photo  through  courtesy  of  the 
Chicago  Creosoting  Co.) 


OPERATION  OF  WOOD  PRESERVING  PLANTS  103 

coupled  to  the  exhaust  ends  of  all  these  coils.  Air  is  at  times 
passed  through  the  storage  tanks  in  order  to  keep  the  composition 
of  the  preservative  uniform. 

Gauges  and  Scales. — Many  plants  are  still  careless  in  their 
methods  of  measuring  absorptions  of  preservative.  Of  course,  if 
the  plant  is  doing  its  own  work,  as  in  most  railroad  plants, 
accurate  measurements  of  absorption  are  not  as  essential  as  in 
commercial  plants  treating  on  contract.  However,  in  either 
case,  correct  determinations  are  at  least  desirable.  Several 
methods  of  measuring  absorption  are  in  practice.  The  most 
common  is  to  have  a  float  and  tell-tale  sliding  on  a  vertical  scale 
board,  the  two  connected  by  a  chain  or  fine  piano  or  annealed  wire 
which  runs  over  pulleys.  If  the  float,  tell-tale,  and  pulleys  are 
large,  operating  with  little  friction,  the  scale  board  accurately 
calibrated,  the  chain  or  wire  protected  from  the  wind,  and  the 
preservative,  if  an  oil,  corrected  for  temperature  expansion,  this 
method  is  simple  and  gives  satisfactory  results.  Care  should  be 
taken  to  agitate  the  preservative  as  little  as  possible  in  pumping 
or  blowing  back. 

When  compressed  air  is  forced  into  the  top  of  the  measuring 
tank  the  total  absorption  may  be  determined  by  gauge  glasses 
or  pet  cock  fastened  to  it,  and  a  check  on  the  total  amount  made 
after  the  excess  preservative  has  been  pumped  or  blown  back 
from  the  retort. 

If  the  measuring  tank  is  mounted  on  a  scale,  the  absorption 
may  be  read  directly  from  the  scale  beam  in  pounds.  This 
renders  corrections  for  temperature  expansion  unnecessary  in  the 
measuring  tank.  Another  excellent  device  is  to  use  a  mercury 
column  set  at  an  angle  to  the  desired  degree  of  sensitiveness. 
(See  Plate  XI,  Fig.  C.)  Readings  in  pounds  can  thus  be  directly 
and  accurately  obtained.  Care  should  be  taken  to  keep  the  oil  in 
the  gauge  pipes  liquid  and  free  from  air.  A  very  good  check  on 
the  methods  just  described  is  to  weigh  the  timber  on  track  scales 
before  it  goes  into  the  retorts  and  immediately  after  it  comes 
out.  This,  doubtless,  is  the  most  accurate  way  of  determining 
absorption.  It  cannot  be  used,  however,  if  the  timber  is  steamed 
or  boiled  in  oil  while  in  the  retort,  as  such  treatments  change  the 
weight  of  the  untreated  wood.  It  is  by  no  means  easy  to  measure 
accurately  the  amount  of  preservative  the  charge  of  wood  is 
absorbing,  especially  during  treatment,  and  this  is  largely  a 
matter  dependent  upon  the  skill  of  the  operator.  A  very  im- 


104        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

portant  aid  in  gauging  absorption  is  to  have  accurate  ther- 
mometers in  all  tanks  used  during  the  treatment. 

Piping. — The  importance  of  using  sharp,  clean  threads  in  mak- 
ing pipe  connections  has  already  been  emphasized.  Too  much 
emphasis  cannot  be  laid  upon  this  detail.  It  is  also  highly 
desirable  to  make  all  pipe  lines — especially  those  for  trans- 
ferring oil — as  short  as  possible,  and  to  provide  a  system 
whereby  then  can  be  completely  drained,  with  a  sump  if  neces- 
sary. Otherwise,  trouble  may  be  experienced  with  the  oil  con- 
gealing in  the  pipes.  Another  essential  is  to  use  only  high-grade 
gate  valves  with  replaceable  wearing  parts  in  all  lines  for  trans- 
ferring liquid,  and  to  pack  these  with  material  not  attacked  by  the 
preservative.  A  precaution  against  leaks  or  breakage  is  to  have 
duplicate  valves  in  all  important  lines.  As  considerable  dirt, 
pieces,  of  bark,  etc.,  fall  from  the  timber,  all  lines  transferring  pre- 
servative from  the  retorts  should  be  protected  with  perforated 
plates  or  screens.  A  "mud  drum"  placed  below  the  retorts  is  a 
good  precaution.  If  these  safeguards  are  not  taken,  the  valves  run 
a  decided  risk  of  being  either  damaged  or  destroyed. 

Shower  Baths. — Under  best  operating  conditions  a  wood-pre- 
serving plant  is  none  too  clean  a  place  for  workmen.  Those 
companies  which  have  installed  locker  rooms  and  shower  baths 
for  their  men  have  found  their  investment  a  paying  one.  Since 
these  can  be  installed  at  small  expense,  they  are  recommended. 

Inspector's  Laboratory. — Too  frequently  an  inspector's  or 
chemical  laboratory  is  either  omitted  entirely,  or  when  an  at- 
tempt is  made  to  furnish  one,  it  is  a  good  place  to  avoid.  This 
is  bad  business  policy,  as  the  most  progressive  companies  have 
discovered.  While,  of  course,  an  elaborate  outfit  is  not  neces- 
sary, the  place  should  be  clean,  well  lighted,  comfortable,  and 
equipped  with  proper  apparatus.  In  brief,  the  inspector's 
laboratory  should  contain  a  detailed  map  of  the  plant,  showing 
all  valves  and  pipe  lines,  with  tables  giving  the  dimensions  of  all 
essential  plant  units.  It  should  have  tools,  such  as  rules,  tapes, 
a  brace  and  bit,  saws,  and  hatchets,  for  studying  the  penetra- 
tions, and  standard  tables  for  ready  reference;  apparatus  and 
chemicals  for  analyzing  the  preservative,  including  retorts, 
flasks,  beakers,  pipettes,  hydrometers,  etc.,  and  a  chemical 
balance.  While  not  absolutely  necessary,  a  drying  oven  for 
studying  moisture  in  wood  and  a  refractometer  for  studying 
oils  will  also  be  found  helpful.  Samples  of  wood  properly  iden- 


OPERATION  OF  WOOD  PRESERVING  PLANTS  105 

tified  as  to  kinds  and  showing  proper  treatment  will  also  be  found 
valuable.  Some  companies  have  not  only  equipped  their  plants 
with  such  laboratories,  but -.have  furnished  a  small  experimental 
plant.  Unfortunately,  the  press  of  daily  routine  almost  in- 
variably prevents  4he  operators  from  carrying  on  experiments 
in  them. 

Fire  Protection. — The  best  fire  protection  lies  in  proper  pre- 
vention through  wise  design  and  efficient  operation.  Under 
such  conditions  danger  from  fire  is  very  slight.  However,  as 
added  precaution  and  to  meet  underwriters'  requirements,  a 
good  fire  pump  is  highly  desirable.  In  addition,  the  water  stor- 
age tank  can  be  drawn  upon.  Fire  hydrants  should  also  be  in- 
stalled in  the  yard  and  properly  maintained.  Some  plants  leave 
fire  lanes  between  the  piles  of  timber  30  or  more  feet  in  width. 
Boxes  of  sand  protected  against  rain  and  equipped  with  shovels 
are  an  excellent  safety  factor,  as  well  as  hand  chemical  extin- 
guishers hung  at  vital  points  in  the  plant. 

Lighting  Equipment. — As  the  plants  are  often  called  upon  to 
run  at  night,  the  dynamos  should  be  sufficiently  powerful  to  not 
only  light  the  plant  proper  but  also  arc  lights  in  the  yard.  As  a 
general  rule,  however,  loading  and  unloading  of  material  should 
be  confined  as  much  as  possible  to  the  daytime,  leaving  only  the 
treatments  for  night  work. 

Sawmill  and  Block  Equipment. — Several  wood-preserving 
plants  in  the  United  States  are  equipped  with  small  sawmills  to 
frame  their  timbers  before  treatment.  The  framing  of  such  tim- 
bers before  the  preservative  is  injected  is  good  practice,  as  it 
insures  a  protection  to  the  wood  over  its  entire  surface.  In  fact, 
ideal  practice  would  be  to  have  the  timber  framed  to  the  exact 
dimensions  required  so  that  no  cutting  or  boring  would  be  re- 
quired after  it  has  been  treated.  There  is  nothing  novel  about  the 
construction  or  operation  of  these  sawmills.  They  can  be  located 
at  any  convenient  place  in  the  yard  and,  as  a  matter  of  safety, 
some  distance  from  the  treating  plant. 

The  manufacture  of  wood  blocks  is  almost  invariably  done  in 
connection  with  the  treating  plant,  the  timber  being  received  in 
planks  and  sawed  into  the  various  sizes  of  blocks  required. 
The  planks  are  carried  by  chain  conveyors  to  the  saws, 
which  are  spaced  so  as  to  cut  them  into  the  desired  depth  of 
block.  In  some  plants  the  saws  are  all  arranged  on  the  same  axis 
and  the  blocks  all  cut  at  one  time.  In  others  the  planks  are  first 


106        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

cut  into  smaller  planks,  which  are  in  turn  cut  into  blocks,  it  being 
claimed  that  this  economizes  in  wood  consumption,  as  knots,  etc., 
can  be  trimmed  with  least  waste.  The  blocks  then  fall  from  the 
saws  onto  a  conveyor,  which  either  carries  them  to  a  bin,  or, 
preferably,  direct  to  the  cylinder  cars,  into  which  they  are  dumped 
by  gravity.  A  good  design  is  to  have  the  cylinder  cars  on  a  track 
paralleling  the  block  conveyor.  As  the  blocks  are  carried  along 
the  conveyor  they  can  be  inspected  and  all  defective  blocks  re- 
moved. By  having  small  swinging  gates  along  the  side  of  the 
conveyor,  the  operator  can  open  one,  using  it  to  deflect  the  blocks 
into  the  cylinder  car  below,  and  after  this  has  been  filled,  close 
the  gate  and  open  the  next  one  situated  further  on,  thus  deflecting 
the  blocks  into  the  second  car,  and  so  on  until  the  entire  charge 
is  filled.  This  method  works  very  efficiently  and  minimizes 
labor.  The  rate  at  which  the  blocks  can  be  manufactured  varies, 
of  course,  upon  the  size  and  speed  of  the  machine  and  depth  to 
which  the  blocks  are  cut.  A  good  machine,  however,  should 
turn  out  200  square  yards  of  4-inch,  blocks  per  hour. 

The  Chicago  Creoso'ting  Company  has  recently  taken  out  pat- 
ents on  a  new  type  of  plant  for  treating  paving  blocks  which  does 
away  entirely  with  cylinder  cars  and  enables  a  decreased  cost  in 
operation.  Their  cylinders,  which  are  11  feet  in  diameter  and  14 
feet  high,  are  built  vertical,  the  blocks  being  carried  on  a  con- 
veyor and  dumped  automatically  into  the  cylinder.  The  treat- 
ment is  then  conducted  in  the  usual  manner,  after  which  the 
door  in  the  bottom  of  the  retort  is  opened  and  the  blocks  fall 
directly  into  cars  for  shipment.  (See  Plate  XI,  Fig.  D.) 

Tie-boring  and  Adzing  Machines. — At  present  few  treating 
plants  consider  tie-boring  and  adzing  machines  as  a  fixed  part 
of  their  equipment.  There  is  no  doubt  but  what  such  machines 
are  a  desirable  asset  to  any  plant  which  is  treating  large  quantities 
of  ties,  and  that  they  will  be  viewed  with  increasing  favor  because 
of  the  excellent  results  secured  from  them.  These  machines  at 
present  are  generally  mounted  upon  a  portable  platform  such  as 
an  improvised  box  car  and  are  driven  by  a  gas  engine.  (See 
Plate  XII,  Fig.  A-Plate  XII,  Fig.  B.)  The  rough  ties  are  placed 
on  a  conveyor  which  automatically  passes  the  ties  through  the 
machine,  where  they  are  adzed  and  bored.  Other  attachments 
are  sometimes  used,  such  as  a  device  for  trimming  the  ties  to  exact 
length,  and  a  die  or  punch  which  brands  them  on  the  ends,  this 
giving  the  date,  kind  of  treatment  or  species  of  wood.  The  ties 


PLATE  XII 


FIG.  A. — Ties  entering  boring  and  adzing  machine.     (Photo  through  cour- 
tesy of  the  Greenlee  Bros.  Co.) 


FIG.  B. — Ties  adzed  and  bored  being  piled  on  the  cylinder  cars  ready  for 
treatment.     (Photo  through  courtesy  of  the  Greenslee  Bros.  Co.) 

(Facing  page  106.) 


PLATE  XII 


FIG.  C. — Section  through  an  oak  tie  showing  a  cut  and  screw  spike 
driven  in !  place.  Note  comparative  distortion  of  wood  fibers.  (Photo 
through  courtesy  of  the  Spencer-Otis  Co.) 


OPERATION  OF  WOOD  PRESERVING  PLANTS  107 

then  pass  down  a  conveyor  on  the  opposite  side  of  the  car,  where 
they  are  piled  either  in  stacks  or  directly  upon  cylinder  cars  for 
treatment.  The  capacity  of  these  machines  varies  but  averages 
about  3000  ties  per  10-hour  d^y.  The  advantages  of  such  treat- 
ment are  given  in  greater  detail  in  Chapter  VIII.  The  total  cost 
of  adzing  and  boring  ties  varies  from  about  1  1/4  to  2  cents  each. 

The  Operation  of  Pressure  Plants. — The  operation  of  pressure 
wood-preserving  plants  varies  widely,  depending  upon  local 
conditions,  the  opinion  of  the  engineer  in  charge,  and  the  proc- 
esses used.  The  latter  have  been  described  in  detail  in  Chapter  V 
but  we  will  discuss  here  the  effect  of  the  various  manipulations 
more  or  less  common  to  all  plants.  Unfortunately,  the  amount 
of  exact  data  available  is  very  meager,  and  results  are  often  se- 
cured without  knowing  why;  hence  the  success  or  failure  of  a  treat- 
ment depends  very  largely  upon  the  experience  of  the  operator. 

The  Effect  of  Vacuum. — A  vacuum  may  be  drawn  in  the  treat- 
ing cylinder  before  the  preservative  is  admitted,  or  after  the  pre- 
servative has  been  forced  into  the  timber,  or  both  before  and 
after.  When  drawn  before  admission  of  preservative,  it  is  re- 
ferred to  as  a  " preliminary  vacuum."  If  drawn  after  injection 
it  is  called  a  "final  vacuum." 

As  stated  in  Chapter  IV,  a  preliminary  vacuum  drawn  imme- 
diately after  the  timber  has  been  steamed  helps  to  dry  the  timber. 
The  reduced  pressure  in  the  cylinder  lowers  the  boiling  point  of 
water  and  hence  hastens  the  rate  with  which  it  evaporates. 
When  a  preliminary  vacuum  is  drawn  on  air-seasoned  wood  it 
also  tends  to  slightly  dry  the  wood  and  remove  an  appreciable 
amount  of  air  from  it.  If,  now,  the  preservative  is  admitted  to 
the  cylinder  without  breaking  the  vacuum,  the  speed  with  which 
the  cylinder  fills  is  increased.  Furthermore,  the  preservative 
can  usually  be  forced  into  the  wood  in  a  shorter  time  and  with 
less  difficulty.  But  the  most  noticeable  effect  is  the  manner  in 
which  the  preservative  is  held  in  the  wood  after  the  pressure  is 
released  (Fig.  11).  It  will  be  noticed  that  only  a  comparatively 
small  amount  of  it  rebounds  or  drips  from  the  timber.  The 
absence  of  large  amounts  of  air  in  the  wood  cells  is  undoubtedly 
the  cause  of  this,  since  on  the  release  of  pressure  there  is  not  suf- 
ficient expansion  of  this  air  in  the  wood  to  force  out  much  of  the 
preserving  fluid.  In  order  to  leave  the  greatest  amount  of 
preservative  in  a  given  stick  of  timber,  therefore,  a  preliminary 
vacuum  should  be  used.  This  fact  is  of  prime  importance  in 


108        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


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FIG.  11. — Showing  the  effect  of  air  in  ties  upon  the  amount  of  creosote 

retained  in  them. 


OPERATION  OF  WOOD  PRESERVING  PLANTS  109 

treating  timbers  which  are  resistant  to  absorption  or  when 
large  absorptions  are  desired.  The  greater  the  intensity  of  the 
vacuum,  the  better  will  be  this  result,  and,  if  possible,  at  least  26 
inches  should  be  obtained.  Tfce  length  of  time  the  vacuum  should 
be  held  depends  chiefly  upon  the  kind  and  size  of  timber  being 
treated.  Porous  woods  like  maple  and  red  oak  require  a  shorter 
vacuum  period  than  resistant  woods  like  hemlock  and  tamarack. 
Small  size  timbers  require  a  shorter  vacuum  period  than  large 
size.  Exact  periods  for  all  species  and  sizes  of  wood  are  not 
definitely  known.  Some  attempts  to  secure  data  on  the  rate  at 
which  a  vacuum  can  be  drawn  on  the  interior  of  air-seasoned 
ties  were  made  at  the  U.  S.  Forest  Products  Laboratory  by  boring 
a  hole  to  the  center  of  the  tie  and  inserting  a  small  pipe  connected 
with  a  vacuum  gauge  fastened  to  the  shell  of  the  cylinder, 
and  thus  drawing  a  vacuum  in  the  cylinder.  It  was  found  that 
in  the  porous  woods  like  red  oak  the  vacuum  on  the  inside  ap- 
proached that  on  the  outside  much  more  rapidly  than  in  the  more 
resistant  woods  like  hemlock.  Of  course,  it  is  not  necessary  to 
secure  as  great  a  vacuum  in  the  center  of  timber  as  in  the  outside, 
because  the  preservative  can  rarely  be  forced  to  the  center,  espe- 
cially in  large-sized  sticks,  but  the  closer  this  can  be  obtained,  the 
more  beneficial  will  be  the  results. 

To  sum  up  the  effect  of  a  preliminary  vacuum : 

1.  More  preservative  is  absorbed  during  the  filling  of  the  cylinder  than 
when  no  preliminary  vacuum  is  used  (Fig.  12).     This  is  especially  true  in 
porous  woods  like  loblolly  pine. 

2.  It  reduces  the  length  of  time  pressure  must  be  held  in  the  cylinder  in 
order  to  secure  the  desired  absorption.     This  difference  is  apparently  very 
slight  in  woods  of  moderate  porosity  like  maple,  but  considerable  in  porous 
or  resistant  woods  like  loblolly  pine  or  hemlock  (Fig.  12). 

3.  It  reduces  to  a  minimum  the  rebound  or  "kickback"  of  the  preserva- 
tive on  the  release  of  pressure  in  the  cylinder  (Fig.  12). 

4.  It  reduces  to  a  minimum  the  amount  of  drip  (Fig.  12). 

5.  It  enables  very  heavy  absorptions  to  be  more  easily  obtained. 

6.  It  tends  to  produce  very  unequal  penetrations  and  absorptions  if  only 
small  amounts  of  preservative  are  forced  into  wood  and  hence  should  not  be 
used  in  such  cases. 

A  final  vacuum  produces  the  opposite  effect  of  a  preliminary 
vacuum  in  that  it  tends  to  remove  the  preservative  from  the  wood. 
It  is  greatly  aided  in  doing  this  if  air  is  left  in  the  wood  or  if  the 
wood  is  treated  with  compressed  air  before  the  preservative  is 
admitted.  The  vacuum  causes  this  air  to  expand  and  force  out 


110         THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


OPERATION  OF  WOOD  PRESERVING  PLANTS 


111 


112        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  preservative.  A  final  vacuum  is  drawn  either  to  dry  the 
timber  and  thus  reduce  loss  of  preservative  through  drip,  or  to 
withdraw  a  portion  of  the  preservative  (see  description  of  "  empty- 
cell"  processes),  or  to  do  both.  In  the  tests  referred  to  above,  a 
final  vacuum  was  drawn  on  some  of  the  ties  and  its  effect  in  re- 
covering creosote  is  shown  in  Figs.  13  and  14.  In  these  tests 
the  amount  of  preservative  recovered  was  about  10  percent  more 
than  when  no  final  vacuum  was  drawn,  being  greatest  in  woods 
easily  treated  and  least  in  those  which  are  resistant  to  injection. 
It  should  be  noted  that  if  a  preliminary  vacuum  is  used  in  con- 
nection with  a  final  vacuum,  a  very  small  recovery  of  oil  is  se- 
cured, hence  in  heavy  treatments  both  may  be  used  to  advantage. 


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FIG.  14.  —  Showing  the  effect  of  air  in  ties  upon  the  "kickback"  with  creosote. 

To  sum  up  the  effect  of  a  final  vacuum  : 

1.  It  dries  the  ties  and  hence  reduces  drip  (Fig.  13). 

2.  It  removes  some  of  the  preservative  injected  into  the  ties,  although 
this,  in  itself,  is  apparently  not  great,  but  may  be  appreciable  if  used  in  con- 
nection with  a  preliminary  or  atmospheric  air  pressure  (Figs.  13  and  15). 

The  Effect  of  Air  Pressure-  —  Air  pressure  is  used  either  before 
or  after  the  preservative  is  forced  into  the  wood;  hence,  as  with 
the  vacuum,  we  have  "  preliminary  "  and  "  final"  air  pressures. 

Preliminary  air  pressures  are  used  to  force  a  portion  of  the 
preservative  out  of  the  wood  and  hence  give  an  "  empty  cell" 


OPERATION  OF  WOOD  PRESERVING  PLANTS 


113 


treatment.  (See  Rueping  Process.)  As  would  be  expected,  it 
can  be  forced  more  easily  into  porous  than  nonporous  woods. 
If  a  preservative  is  forced  into  wood  filled  with  compressed  air 


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10         20        30        40         50        GO        70         80         90       100 
Preliminary  Cylinder  Condition-  Lbs.  per  SOL.  In.  (Absolute) 

FIG.  15. — Showing  the  effect  of  air  in  ties  upon  the  amount  of  creosote 
recovered  by  a  final  vacuum  and  drip. 

and  the  pressure  on  the  preservative  is  then  released,  the  air  in 
the  wood  will  expand  and  force  out  a  part  of  the  preservative. 
Some  data  on  the  amount  thus  forced  out  is  shown  in  Figs.  12 
and  13.  It  will  be  noted  that  the  amount  of  air  forced  out  varies, 

8 


114        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


up  to  a  certain  ratio,  with  the  amount  of  air  forced  into  the  wood, 
and  that  a  final  vacuum  increases  this  amount  (Fig.  15).  It  has 
been  noticed,  however,  that  it  takes  the  compressed  air  in  wood 


led  Oak 


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10        20        SO        40        50        CO        70        80        90      100 
Preliminary  Cylinder  Condition  -Lbs.  Per  Sq.  In.  (Absolute) 


a  long  time  to  escape — several  days  in  some  cases — and  that  this 
causes  either  a  large  drip  or  volatilization  of  preservative  or  both. 

The  effect  of  a  preliminary  air  pressure  is,  then,  to : 

1.  Increase  the  amount  of  preservative  absorbed  during  the  filling  of  the 


OPERATION  OF  WOOD  PRESERVING  PLANTS  115 

cylinder  over  what  is  absorbed  when  only  atmospheric  pressure   is  used 
(Fig.  16). 

2.  Increase  the  length  of  time  pressure  must  be  held  on  the  preservative  in 
order  to  obtain  the  desired  absorption.     This  is  but  slight,  however,  in 
woods  like  red  oak  but  considerable  in  resistant  woods  like  hemlock  (Fig. 
12). 

3.  Increase  the  amount  of  preservative  which  rebounds  or  "kickback" 
from  the  wood  on  release  of  pressure  (Fig.  12). 

4.  Increase  the  amount  of  drip  (Figs.  12,  13). 

5.  Leave  a  minimum  amount  of  preservative  in  the  wood  (Fig.  14). 

A  "  final  air  pressure "  is  seldom  used.  It  was  originally  ad- 
vocated to  force  the  preservative  deeper  into  the  wood  and  thus 
produce  an  " empty-cell"  effect.  While  it  tends  to  do  this  to  a 
slight  extent,  nevertheless  it  exerts  a  more  pronounced  action 
in  removing  some  of  the  preservative.  This  is  probably  due  to 
the  fact  that  when  pressure  is  released  the  air  escapes  from  the 
wood  and  carries  some  of  the  preservative  with  it, 

The  Effect  of  Pressure  on  the  Preservative. — In  applying 
pressure  to  a  preservative  in  a  treating  cylinder  three  factors  are 
of  importance:  The  intensity  of  the  pressure,  the  duration  of 
the  pressure,  and  the  rate  at  which  the  pressure  is  applied. 

lii  general,  the  higher  the  pressure  the  greater  and  more  rapid 
the  penetration.  On  porous  woods,  high  pressures  are  not  neces- 
sary and,  in  fact,  often  objectionable  because  they  force  the  pre- 
servative too  rapidly  into  the  wood  and  cause  irregular  penetra- 
tions. With  resistant  woods,  high  pressures  (175  pounds  per 
square  inch  or  over)  are  also  of  little  value  because  the  resistance 
of  the  wood  is  often  so  great  that  the  application  of  excessive  pres- 
sure— even  500  pounds  per  square  inch  or  more — is  not  suffi- 
cient to  overcome  this  resistance.  Working  pressures  of  from 
100  to  150  pounds  per  square  inch  give  most  general  satisfaction. 

As  the  wood  cells  are  minute  and  the  channels  through  which 
the  large  portion  of  the  preservative  passes  are  frequently  micro- 
scopic in  size,  it  is  necessary  to  allow  sufficient  time  for  the  pre- 
servative to  diffuse  through  them.  If  the  desired  absorption 
of  preservative  is  secured  in  a  short  period,  the  penetration  is 
apt  to  be  very  irregular,  whereas  if  the  same  absorption  is  ob- 
tained in  a  longer  period  a  more  uniform  distribution  is  generally 
secured.  The  ideal  result  is  to  have  the  preservative  diffused 
through  the  wood  uniformly  and  deeply.  The  application  of  a 
lower  pressure  held  for  a  longer  time  approaches  this  result  better 
than  a  high  pressure  held  for  a  short  time.  Its  chief  disadvantage 


116        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

is  a  decrease  in  the  capacity  of  the  plant.  The  rate  at  which  the 
pressure  is  applied  to  the  preservative  is  also  important.  If  it  is 
applied  rapidly  up  to  the  maximum,  and  the  maximum  is  high, 
the  desired  absorption  will  be  obtained  in  the  shortest  time  but 
at  the  expense  of  greatest  diffusion.  A  rapid  application  of 
pressure  with  a  comparatively  low  maximum  is  better  practice. 
If,  however,  the  operator  wants  capacity,  and  a  large  rebound  or 
" kickback"  of  preservative  after  the  pressure  is  released,  a 
rapid  application  of  high  pressure  is  the  thing  to  use.  The  erratic 
penetration  due  to  a  quick  absorption  may  be  compensated  for, 
in  part  at  least,  if  the  operator  forces  into  the  wood  more  pre- 
servative than  he  intends  to  leave  in  it,  and  counts  upon  the 
"kickback"  to  remove  the  surplus  preservative.  As  has  been 
shown  above,  the  condition  of  the  air  in  the  timber  also  produces 
a  marked  effect  upon  the  amount  of  preservative  which  rebounds 
out  of  the  wood  when  pressure  is  released. 

Some  Common  Errors  and  Difficulties  in  Operating  Pressure 
Plants. — Even  in  the  best  equipped  and  managed  plants,  mechan- 
ical errors  and  difficulties  in  operation  are  almost  daily  encoun- 
tered. Without  going  into  the  details  characteristic  of  each  proc- 
ess, the  following  general  notes  may  be  found  of  service,  particu- 
larly to  operators  and  inspectors. 

Difficulty  of  Measuring  Volume  of  Charge. — The  volume  of 
the  timber  in  the  treating  cylinder  could  easily  be  determined, 
irrespective  of  its  form,  by  subtracting  the  quantity  of  preserva- 
tive it  takes  to  fill  the  cylinder  when  charged  from  that  necessary 
to  fill  it  when  empty,  and  deducting  the  volume  of  the  cars,  were 
it  not  for  the  fact  that  the  wood  will  absorb  the  preservative 
while  the  cylinder  is  being  filled.  The  amount  absorbed  varies 
with  the  kind  and  condition  of  the  wood,  being  greatest  in  the 
case  of  porous  woods  air-dry  and  least  for  resistant  woods  when 
green,  but  generally  ranges  from  about  5  to  20  percent.  Some 
treating  plants  allow  for  this  "  initial  absorption,"  and  deduct 
10  percent  from  the  total  amount  of  preservative  to  be  forced 
into  the  wood  after  pressure  is  applied.1  There  is  no  satisfactory 
way  of  determining  just  what  this  initial  absorption  will  be,  and 
it  must  be  worked  out  through  experience  at  each  plant.  The 

1  Some  treating  engineers  claim  that  blowing  the  preservative  out  of  the 
treating  cylinder  into  the  measuring  tank  also  blows  some  of  the  preserva- 
tive out  of  the  wood,  especially  if  it  is  porous.  As  shown  above  (see  "final 
air  pressure"),  this  is  quite  likely  to  occur. 


OPERATION  OF  WOOD  PRESERVING  PLANTS  117 

volume  of  sawed  timbers  can  usually  be  determined  with  suffi- 
cient accuracy  by  direct  calculation. 

Expansion  of  Creosote. — Creosote  expands  considerably  when 
heated,  averaging  jabout  1  "^percent  for  every  22  1/2°  F.  rise  in 
temperature.  It  is  frequently  run  into  the  'treating  cylinder  at 
about  200°  F.  and  its  temperature  invariably  falls  from  10°  to  60° 
when  it  strikes  the  timber.  Unless  brought  back  to  its  tempera- 
ture at  entrance  this  contraction  may  be  charged  against  absorp- 
tion. Similar  errors  will  be  introduced  in  taking  the  final  reading 
of  absorption  when  the  height  of  the  oil  in  the  measuring  tank 
after  the  treatment  has  been  completed  is  subtracted  from  the 
height  before  treatment,  unless  the  temperature  at  both  times  is 
the  same.  It  is  important,  therefore,  to  keep  the  temperature  of 
the  oil  as  nearly  constant  as  possible  (with  no  greater  variation 
than  20°  F.) ;  or,  if  this  cannot  be  done,  to  correct  for  tempera- 
ture errors  by  using  the  proper  coefficients  of  expansion.  For 
zinc  treatments  and  others  of  a  similar  nature  such  corrections 
need  not  be  made. 

Expansion  of  the  Cylinder. — When  hot  creosote  enters  the 
comparatively  cool  treating  cylinder  it  produces  an  expansion  of 
the  metal,  which  is  further  augmented  by  an  internal  pressure 
often  as  high  as  175  pounds  per  square  inch.  For  ac  ylinder  made 
of  3/4-inch  boiler  steel,  7  feet  in  diameter  and  132  feet  in 
length,  this  increase  in  volume  may  amount  to  about  18  cubic 
feet,  equivalent  to  an  absorption  of  about  1187  pounds  of 
preservative. 

Compression  of  the  Oil  and  Wood. — When  pressure  is  ap- 
plied to  creosote  the  oil  is  compressed.  At  most,  however,  this 
can  produce  only  an  insignificant  error,  since  creosote  under 
.ordinary  operative  conditions  compresses  less  than  one-tenth  of  1 
percent.  The  error  due  to  the  compressibility  of  the  wood  is  also 
insignificant.  Some  tests  were  made  at  the  U.  S.  Forest  Prod- 
ucts Laboratory  in  which  20  pieces  of  green  red  oak  and  black 
oak,  2  by  2  inches  in  cross  section,  were  tested  in  a  100,000- 
pound  machine,  the  load  being  applied  radially  and  tangentially. 
The  average  modulus  of  elasticity  was  50,375  pounds  per  square 
inch.  Disregarding  the  longitudinal  dimension,  the  volumetric 
compression  due  to  an  exterior  pressure  of  200  pounds  per  square 
rnch  ranged  from  0.51  to  1.30  percent,  or  an  average  of  0.80  per- 
cent. This  compression  is  probably  much  in  excess  of  that  which 
takes  place  in  practice,  since  when  wood  is  submerged  in  a 


118        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

preservative  fluid  the  pressure  is  applied  from  all  directions. 
Furthermore,  at  least  a  part  of  this  pressure  is  transmitted  to 
the  interior.  It  would  seem,  therefore,  that  the  decrease  in  the 
volume  of  wood  undergoing  treatment,  due  to  the  pressure 
exerted  on  it,  can  be  entirely  disregarded. 

" Kickback"  of  Preservative. — When  pressure  is  applied  to  a 
cylinder  charge,  the  oil,  wood,  and  air  confined  in  the  wood  are 
under  compression  and  the  cylinder  is  under  tension.  If  the  pres- 
sure is  released  a  certain  amount  of  the  preservative  will  be  forced 
out  of  the  cylinder,  although  it  remains  constantly  full.  The 
amount  of  preservative  thus  forced  out  will  be  called  the  "kick- 
back." It  varies  with  many  conditions,  and  unless  provided 
for  may  result  in  errors  of  measurement  for  absorption  of  from 
10  to  40  percent.  In  the  treatment  of  air-seasoned  red  oak  and 
maple  ties  at  the  U.  S.  Forest  Products  Laboratory  by  the  full- 
cell  process  it  was  necessary,  after  the  desired  absorption  had 
been  reached,  to  allow  from  20  to  30  percent  for  the  oil  which  did 
not  remain  in  the  ties. 

To  secure  data  on  the  variability  of  the  " kickback"  a  careful 
series  of  tests  was  run  on  36  pieces  of  air-dry  longleaf  pine.  These 
were  cut  2  inches  by  4  inches  by  4  feet,  matched,  divided  into 
three  groups  of  12  each,  and  treated  in  three  different  runs  in  a 
cylinder  approximately  18  inches  in  diameter  and  4  feet  long. 
In  all  cases  the  drip  was  stopped  when  it  amounted  to  less  than 
1/2  pound  of  creosote  in  a  half-hour  period.  The  runs  were 
made  as  follows: 

Run  1. — No  preliminary  or  final  vacuum  was  used.  The 
cylinder  was  filled  with  creosote  in  6  minutes  and  the  oil  raised 
to  a  temperature  of  180°  F.  A  pressure  of  120  pounds  per 
square  inch  was  immediately  applied  and  held  for  7  minutes. 
The  pressure  was  then  released  through  the  top  of  the  cylinder 
for  15  minutes,  after  which  the  cylinder  was  drained  and  the 
wood  permitted  to  drip  for  121  minutes,  when  it  was  removed 
and  weighed. 

Run  2. — After  the  wood  was  placed  in  the  cylinder  a  prelimi- 
nary vacuum  of  25  1/2  inches  was  held  for  15  minutes,  the  total 
vacuum  period  amounting  to  22  minutes.  Without  breaking 
the  vacuum  the  creosote  was  then  drawn  into  the  cylinder,  the 
operation  consuming  5  minutes.  The  temperature  of  the  creo- 
sote on  entering  the  cylinder  dropped  to  125°  F.  It  was  raised 
to  181°  F.  in  12  minutes,  when  a  pressure  of  120  pounds  per 


OPERATION  OF  WOOD  PRESERVING  PLANTS  119 

square  inch  was  immediately  applied  and  held  for  3  minutes. 
The  pressure  was  then  released  for  16  minutes  through  the  top 
of  the  cylinder,  after  which  the  cylinder  was  drained  and  the 
wood  permitted  to  drip  for  73  minutes,  when  the  charge  was 
removed  and  weighed. 

Run  3. — A  preliminary  air  pressure  of  50  pounds  per  square 
inch  was  immediately  applied  and  held  for  15  minutes,  after 
which  the  oil  was  pumped  into  the  cylinder  against  this  pressure, 
the  operation  taking  about  10  minutes.  The  temperature  of  the 
oil  on  entering  the  cylinder  dropped  to  156°  F.  It  was  then 
raised  to  180°  F.,  consuming  9  minutes.  During  the  heating 
period  the  pressure  in  the  cylinder  varied  between  55  and  70 
pounds  per  square  inch.  As  soon  as  the  oil  reached  180°  F.  a 
pressure  of  120  pounds  per  square  inch  was  applied  and  held 
for  78  minutes.  The  pressure  was  then  released  through  the 
top  of  the  cylinder  for  14  minutes,  after  which  the  cylinder  was 
drained  and  the  wood  permitted  to  drip  for  128  minutes,  when 
the  charge  was  removed  and  weighed. 

The  results  of  these  runs  are  given  in  Table  7.  It  will  be  seen 
that  the  " kickback"  was  least  when  a  preliminary  vacuum  was 
drawn,  and  greatest  when  the  cylinder  was  first  filled  with  com- 
pressed air.1  Similar  results  were  secured  on  full-sized  ties,  as 
is  shown  in  Figs.  12  and  13. 

To  illustrate  the  possible  source  of  error  through  this  "  kick- 
back" on  the  release  of  pressure,  suppose,  for  example,  it  amounts 
to  20  percent,  and  the  specifications  call  for  a  10-pound  per  cubic 
foot  injection  in  cross-ties  of  3.5  cubic  feet  each.  If  the  "kick- 
back" is  disregarded  and  the  pumps  kept  running  until  the  gauges 
show  an  injection  of  10  pounds  per  cubic  foot  and  the  pressure  is 
then  released,  only  8  pounds  per  cubic  foot  will  be  left  in  the  ties. 
If,  on  the  other  hand,  the  " kickback"  is  considered,  then  the 
pumps  will  be  kept  running  until  the  gauges  indicate  an  absorp- 

1  When  the  preliminary  vacuum  was  drawn,  only  3  minutes  of  oil  pressure 
were  required  to  force  12.3  pounds  of  oil  per  cubic  foot  into  the  wood,  but 
when  the  cylinder  and  wood  were  first  filled  with  compressed  air  it  took  78 
minutes  to  force  12  pounds  of  oil  per  cubic  foot  into  the  wood.  That  the 
preliminary  vacuum  rendered  it  easier  to  force  the  preservative  into  the 
wood  is  therefore  apparent.  After  the  run  the  sticks  were  split  and  the 
penetration  in  run  3  was  found  to  be  slightly  greater  than  in  runs  1  and  2. 
Furthermore,  the  sticks  in  run  3  were  treated  more  uniformly  than  in  the 
other  runs,  especially  run  2,  in  which  the  penetration  and  absorption  were 
very  irregular. 


120        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


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tion  of  12.5  pounds  per  cubic  foot,  which 
on  the  release  of  pressure  will  leave  10 
pounds  per  cubic  foot  in  the  ties.  If 
this  "kick-back"  is  released  through  an 
underground  tank  or  some  measuring 
tank  other  than  the  one  used  during 
treatment  (and  this  is  a  common  prac- 
tice), the  chances  for  error  in  measur- 
ing the  absorption  are  increased. 

Expansion  of  Wood. — Another  pos- 
sible source  of  error  in  measuring  ab- 
sorption is  the  expansion  of  the  wood 
due  to  raising  its  temperature.  Assum- 
ing the  thermal  coefficient  of  linear  ex- 
pansion of  wood,  0.00001  per  degree 
Centigrade  parallel  to  the  fiber  and 
0.00006  across  the  fiber1  and  that  the 
wood  is  raised  in  temperature  60°  C. 
(140°  F.)  during  treatment,  then  the 
increase  of  volume  in  a  charge  of  say  800 
ties  will  be  about  22  cubic  feet,  equiva- 
lent to  about  1,386  pound  of  creosote, 
or  1.7  pounds  per  tie.  If  the  wood  is 
raised  more  than  60°  C.  in  temperature, 
the  volume  increase  will,  of  course,  be 
greater. 

Extent  of  Possible  Errors. — The  ex- 
tent of  the  various  errors  possible  in 
measuring  absorption  may  be  illustrated 
by  the  following  example:  Assume  the 
treating  cylinder  to  be  7  feet  in  diameter, 
132  feet  long,  and  to  hold  a  charge  of 
800  7-inch  by  9-inch  by  8-ft.  ties;  as- 
sume also  that  10  pounds  of  creosote 
per  cubic  foot  are  to  be  injected  into 
and  left  in  the  ties;  that  a  pressure  of 
175  Ib.  per  square  inch  is  used  during  the 
treatment;  that  the  oil  in  the  measuring 
tank  is  maintained  at  200°  F.  and  is  in- 

1  Experiments  of  Glatzel  and  Villari :  Smith- 
sonian physical  tables,  5th  rev.  ed.,  p.  223. 


OPERATION  OF  WOOD  PRESERVING  PLANTS  121 

jected  into  the  wood  at  180°  F.;  and  that  the  normal  tempera- 
ture of  the  cylinder  and  wood  is  60°  F.  With  all  gauges  work- 
ing perfectly,  no  leaks  o^  'any  kind  occurring,  all  air  out  of  the 
cylinder  when  the  oil  pump  is  started,  and  the  volume  of  the 
ties  accurately  known,  the  Following  errors  may  take  place: 

Pounds 
per  tie 

1.  Chargeable  to  contraction  in  the  volume  of  creosote 1 .85 

2.  Chargeable  to  the  expansion  of  the  cylinder  due  to  temperature       1 . 35 

3.  Chargeable  to  the  "kickback"  (assumed  to  be  20  percent  of  the 

absorption)   7.00 

Total  positive  errors 10.20 

4.  Chargeable  to  the  expansion  of  the  wood  1 . 50 

Total  in  excess  of  apparent  absorption   8.7 

Thus,  out  of  a  total  specified  injection  of  10  pounds  per  cubic 
foot,  or  35  pounds  per  tie,  8.7  pounds  per  tie  may  be  forced 
into  the  cylinder,  but  either  will  not  go  into  or  not  remain  in  the 
ties,  constituting  a  total  error  of  about  25  percent.  In  plants 
operating  with  zinc  chloride,  item  1  may  be  eliminated  and  item 
3  will  be  less  than  that  given. 

Purity  of  the  Preservative. — The  composition  of  the  preserva- 
tive is  subject  to  change  so  that  check  analyses  of  it  should  be 
made  from  time  to  time  to  see  that  it  meets  specifications. 

With  creosote,  the  chief  difficulty  likely  to  occur  is  with  the 
water  content  of  the  oil.  Leaky  steam  coils,  or  snow  or  ice  on 
the  wood,  or  water  in  the  wood  are  all  liable  to  adulterate  the 
oil  with  water.  It  is  not  necessary  to  remove  all  of  the  water 
but  large  amounts  (over  5  percent)  are  objectionable  and  it  is 
not  good  practice  to  allow  for  this  by  giving  the  timber  a  heavier 
injection.  Proper  procedure  is  to  remove  the  water.  This  may 
be  done  in  some  cases  by  allowing  the  oil  to  stand  for  several  days 
in  a  tank,1  when  the  water  may  be  drawn  from  the  top  of  the  oil, 
or  by  boiling  off  the  water  in  tanks  equipped  with  steam  coils. 
In  either  case  loss  of  some  oil  is  almost  sure  to  occur. 

It  sometimes  happens  that  the  carbon  content  of  the  creosote 
will  increase  as  it  is  used  over  and  over  again,  so  that  timber 
treated  with  "old"  oil  will  look  much  blacker  than  timber  treated 
with  "fresh"  oil.  The  author  has  known  of  inspectors  refusing 

1  Some  engineers  alternately  heat  and  cool  the  oil  several  times  before 
drawing  off  the  water. 


122        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

to  accept  treated  timber  because  it  did  not  look  "black."  Free 
carbon  will  not  penetrate  wood,  has  no  preservative  value,  and 
detracts  from  the  quality  of  the  oil.  About  the  only  practical 
way  to  guard  against  too  large  a  percentage  of  free  carbon  is  to 
be  careful  in  the  purchase  of  the  oil. 

It  is  also  asserted,  at  times,  that  the  composition  of  creosote 
changes  because  that  portion  of  it  which  enters  the  wood  and  is 
then  redrawn  carries  with  it  some  of  the  soluble  constituents  in 
the  wood.  While  there  is  a  possibility  of  its  doing  this,  careful 
tests  have  failed  thus  far  to  show  any  marked  changes  in  the  oil 
due  to  this  cause. 

Solutions  of  zinc  chloride  also  need  careful  attention.  Common 
practice  is  to  place  a  hydrometer  in  the  solution  and  if  it  shows 
correct  gravity  to  assume  the  strength  to  be  correct.  This  prac- 
tice is  subject  to  error  because  foreign  substances  such  as  other 
inorganic  salts  or  materials  dissolved  from  the  wood  may  change 
the  gravity.  Some  careful  tests  made  at  the  U.  S.  Forest  Prod- 
ucts Laboratory  have  also  shown  that  the  strength  of  a  zinc- 
chloride  solution  may  be  changed  by  successive  treatments,  the 
solution  tending  to  weaken. 

Pollution  of  Streams. — Complaint  has  been  made  against  some 
treating  plants  because  they  polluted  streams  with  waste  oil. 
This  comes  largely  from  the  cylinders  and  steam  exhausts.  Of 
course,  no  plant  is  going  to  deliberately  waste  preservative  and 
it  is  believed  that  such  complaints  can  be  entirely  avoided  as  they 
are  indications  of  bad  management.  The  use  of  a  final  vacuum 
in  drying  the  timber,  and  attention  to  steam  coils  to  see  that  they 
do  not  leak,  will  remedy  much  of  the  difficulty.  All  drains  can 
be  carried  to  a  common  settling  tank,  where  by  a  system  of  over- 
flow chambers  arranged  in  the  tank  practically  no  oil  will  escape. 

Inspection  of  Treatments. — Controversies  between  purchasers 
of  treated  timber  and  operators  of  treating  plants  over  the  in- 
spection of  treatments  have  been  no  more  common  than  in  other 
industries  which  are  of  comparatively  new  growth  and  where  so 
many  factors  are  involved,  but  much  needless  dispute  has  oc- 
curred because  one  party  or  the  other  has  not  been  sufficiently 
trained  to  recognize  legitimate  demands.  Attempts  to  cover  up 
fraudulent  work  have,  of  course,  been  made  and  probably  will  be 
as  long  as  the  industry  exists,  but  such  cases  are  decidedly  in  the 
minority,  for  corrupt  practice  sooner  or  later  becomes  generally 
recognized  and  eventually  kills  itself. 


OPERATION  OF  WOOD  PRESERVING  PLANTS  123 

Much  of  the  trouble  can  be  laid  entirely  on  the  purchaser,  who 
frequently  insists  upon  impra  ctical  specifications  and  unattainable 
results.  It  is  the  author's  opinion  that  considerable  freedom 
should  be  given  the  operator  as  regards  the  details  of  the  treat- 
ment, and  that  only  a  few  essential  features  need  be  required. 
We  will  attempt  to  give  here  only  those  which  are  more  important 
and  applicable  to  general  conditions. 

First,  perhaps,  comes  the  wood  itself.  It  should  be  remem- 
bered that  wood  is  a  product  grown  under  a  wide  variety  of  con- 
ditions and  hence  varies  greatly  in  its  structure.  It  is  practically 
impossible  to  get  two  pieces  which  are  alike,  and  therefore  speci- 
fications for  wood  should  not  be  too  stringent.  It  is  reasonable  to 
expect,  however,  that  only  sound  wood  be  furnished.  In  this 
connection,  wood  which  is  sap-stained  should  not  be  confused 
with  wood  which  is  decayed.  In  specifying  rings  per  inch,  knots, 
crooks,  tapers,  etc.,  care  should  be  exercised  so  that  the  speci- 
fications are  reasonable  and  do  not  require  the  rejection  of  large 
quantities  of  good  material.  As  regards  the  kinds  of  wood,  the 
specifications  should  recognize  that  the  same  kind  may  go  under  a 
variety  of  names;  hence  no  chance  for  misunderstanding  should  be 
left. 

The  composition  of  the  preservative  to  be  used  should  be  clearly 
stated  and  also  its  method  of  analysis,  and  the  inspector  should  be 
granted  permission  to  take  samples  for  analysis  as  often  and  from 
whatever  source  he  pleases.  Requirements  in  this  regard  can  be 
made  fairly  rigid. 

The  treating  operator  can  also  be  held  to  have  his^'plant]  in 
fit  condition  for  accurate  work,  and  if  considered  necessary  the 
inspector  can  measure  all  essential  pieces  of  apparatus  in  order 
to  make  sure  the  dimensions  furnished  are  correct.  Errors 
in  operation  already  described  should  be  recognized,  so  that  they 
can  be  taken  into  account  in  making  determinations  of  absorption. 
As  for  the  treatment  proper,  the  essentials  to  specify  are  the  maxi- 
mum temperatures  to  be  used  and  the  absorption  of  preservative 
required.  This  should  be  final  absorption,  or  the  amount  of  pre- 
servative actually  in  the  wood  at  the  time  it  is  removed  from  the 
cylinder,  free  from  drip.  Because  wood  varies  so,  it  should  not 
be  expected  that  all  pieces  are  to  have  the  same  absorption.  They 
may  vary  widely.  In  all  cases,  as  deep  and  uniform  a  penetra- 
tion as  possible  should  be  required,  and  the  inspector  should 


124        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

know  what  is  possible  before  he  attempts  to  pass  judgment  on  the 
results.  A  complete  penetration  of  all  sapwood  should  always  be 
secured  and  the  specifications  should  be  so  framed  as  to  admit 
of  this.  Woods  which  vary  widely  in  their  resistance  to  injection 
should  not  be  treated  in  the  same  charge;  neither  should  the 
mixing  of  green  and  seasoned  wood  in  the  same  run  be  allowed. 
In  all  cases  the  difference  in  the  height  of  the  preservative  in  the 
measuring  tank  before  and  after  the  treatment  has  been  made 
should  furnish  the  final  basis  for  determining  the  absorption 
secured;  or  if  seasoned  wood  is  treated,  the  weights  on  the  track 
scales  should  be  used.  Sources  of  error  due  to  friction  of  gauges, 
differences  in  temperatures,  etc.,  should  be  carefully  considered 
in  determining  final  absorption. 

The  Cost  of  Pressure  Plants. — The  cost  of  pressure  plants  is 
exceedingly  variable  even  for  plants  of  the  same  capacity.  Any 
estimate,  therefore,  must  be  considered  with  a  wide  latitude. 
The  variations  in  cost  are  due  largely  to  the  type  of  buildings, 
the  number  of  processes  practised,  the  yard  layout,  and  local 
soil  and  surface  conditions.  The  author  knows,  for  example, 
of  two  plants  with  cylinders  approximately  6  feet  2  inches  in 
diameter  by  132  feet  in  length,  equipped  to  treat  timber  by 
the  same  methods,  one  of  which  cost  $65,000  and  the  other 
$170,000  complete. 

With  these  variations  in  mind,  the  following  estimate  of  a 
2-cylinder  plant  with  cylinders  7  feet  in  diameter  by  132  feet 
in  length,  equipped  to  treat  by  any  standard  process  and  of 
first  class  construction,  is  given : 

Track  and  grading $35,000 

Retorts  with  all  piping  installed 13,000 

Three  150  H.P.  boilers  complete 4,000 

Sewers 1,500 

Buildings 30,000 

Pumps  (compressor,  vacuum,  hydraulic,  service) 5,000 

Piping,  valves,  complete 7,000 

Fire  hydrants  and  equipment 3,500 

Electric  plant  complete 4,000 

Miscellaneous  plant  items 4,000 

One  12-ton  locomotive  crane 4,200 

One  dummy  engine 3,000 

Cylinder  cars  (190) 8,500 


Total $122,700 


OPERATION  OF  WOOD  PRESERVING  PLANTS 


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126        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


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to  60  days  supply  when  running. 
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orking  pressure  of  250  pounds  per  square  inch, 
her  Burnettizing,  Wellhouse,  Full  Cell,  Rueping,  Lowry  or  Card  process, 
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piling  and  timber  it  is  necessary  to  have  a  traveling  yard  crane,  which  will  cost  about  five  to  seven  thousand  dollars,  de- 

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Tie  storage  is  based  on  75 
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Track  is  based  on  60  pounc 
Retorts  are  designed  for  w 
Plants  are  arranged  for  ei 
Hoists  are  for  transferring  1 
Where  plants  are  treating 
jending  on  capacity. 

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93TU01S 

OPERATION  OF  WOOD  PRESERVING  PLANTS  127 

Through  the  courtesy  of  the  Allis-Chalmers  Company,  the 
author  is  able  to  give  Table  8,  which  contains  estimates  of  the 
cost  of  wood  preserving  plants  of  various  capacities.  The  plants 
given  in  the  table  are  arranged  for  either  the  Burnett,  Wellhouse, 
Bethel,  Rueping,  Lowry,  or  Card  process.  In  using  this  table, 
variations  of  at  least  20  percent  either  way  can  be  expected. 


CHAPTER  VIII 

PROLONGING  THE  LIFE  OF  CROSS-TIES  FROM  DECAY 
AND  ABRASION 

Selection  of  Species. — At  the  present  time,  practically  any 
kind  of  tree  which  is  large  enough  to  make  a  cross-tie  is  used  for 
this  purpose.  The  result  is  a  great  variety  of  ties  differing 
widely  in  their  properties.  It  stands  to  reason,  therefore,  that 
the  service  obtained  from  ties  must  be  very  erratic.  The  diffi- 
culty now  generally  experienced  by  many  American  railroads  to 
secure  adequate  supplies  of  good  ties  makes  it  impossible  to  be 
too  stringent  in  specifying  the  kinds  of  wood  which  will  be  used. 
If  planting  trees  for  ties  becomes  general,  the  question  of  proper 
selection  of  species  will  be  a  very  important  one,  but  at  the  pres- 
ent time  this  feature  is  recognized  only  in  the  price  paid  for  ties 
and  no  special  selection  is  made. 

Common  practice  now  consists  in  dividing  the  various  kinds  of 
ties  into  two  groups,  viz.,  ties  to  be  used  without  preservative 
treatment  and  ties  to  be  treated.  The  former  group  includes 
those  woods  which  are  naturally  durable,  the  latter  those  which 
if  placed  in  a  track  untreated  would  decay  in  a  few  years. 

The  ideal  tie  for  use  without  treatment  is  one  which  is  not  only 
very  resistant  to  decay  but  which  is  hard  and  will  hold  spikes 
and  resist  rail  cutting  without  serious  splitting  or  checking.  Of 
our  more  common  American  woods,  black  locust  and  white  oak 
best  meet  these  requirements.  Redwood,  cedar,  and  cypress 
are  very  durable  but  are  inferior  to  black  locust  and  white  oak  as 
regards  strength. 

If  the  tie  is  to  be  treated,  the  prime  qualities  are  strength, 
hardness,  and  permeability.  Red  oak,  maple,  birch,  beech,  and 
elm  best  fulfill  these  conditions.  A  large  variety  of  other  woods 
are,  of  course,  also  used,  chief  among  which  are  the  pines,  firs, 
spruces,  gums,  hemlocks,  chestnut,  and  tamarack.  Irrespective 
of  marketing  conditions,  the  value  of  these  woods  for  tie  purposes 
depends  directly  upon  their  ability  to  meet  the  requirements 
just  mentioned.  In  other  words,  a  wood  which  is  hard  and  por- 

128 


PROLONGING  THE  LIFE  OF  CROSS-TIES  129 

ous  is  more  valuable  for  a  " treatment  tie"  than  a  wood  which 
is  soft  and  resistant  to  impregnation,  and  should  therefore  com- 
mand a  higher  price.  Maple,  for  example,  is  worth  more  for  a 
cross-tie  than  white  pine  or  spruce  because,  when  treated,  it  will 
give  better  service.^ 

Unfortunately,  conditions  are  still  such  in  our  country  that 
many  trees  are  cut  for  ties  which  ought  to  be  cut  for  more  valu- 
able products  such  as  veneer  or  lumber.  Black  walnut,  cherry, 
and  hickory  are  conspicuous  examples.  Where  these  trees  occur 
scattered  in  forests  or  woodlots,  it  is  often  easiest  to  market  them 
in  the  form  of  ties,  but  whenever  possible,  they  should  not  be 
used  for  this  purpose,  as  it  results  in  a  distinct  economic  loss  of 
valuable  material. 

Hewed  Versus  Sawed  Ties. — Approximately  75  percent  of  all 
ties  purchased  are  hewed.  In  the  tie  industry  as  a  whole  the 
methods  of  manufacture  are  undergoing  no  general  or  perma- 
nent changes.  The  probable  reasons  are  that  the  railroads 
obtain,  either  directly  or  indirectly  through  tie  companies,  a 
large  proportion  of  their  ties  from  farmers  and  small  holders  of 
timber  who  cannot  afford  to  saw  them,  and  also  because  the  im- 
portance of  utilizing  timber  to  the  best  advantage  has  not  yet 
been  keenly  felt.  Under  certain  conditions  the  sawing  of  ties 
may  be  impracticable,  as  when,  for  example,  only  a  few  trees 
suitable  for  cross-ties  are  available,  or  when  ties  are  cut  from  tops 
of  felled  trees.  In  such  cases  it  is  much  better  to  utilize  the  wood 
by  hewing  it  into  ties  than  to  leave  it  in  the  forest.  The  claim 
is  often  made  that  hewed  ties  are  more  durable  than  sawed  ties 
because  they  shed  water  better.  Nothing  is  known  by  the  U.  S. 
Forest  Service  to  substantiate  this  impression.  Even  if  untreated 
hewed  ties  should  be  more  durable  than  sawed  ones,  this  advan- 
tage disappears  when  the  ties  are  treated.  On  the  other  hand 
there  are  many  serious  objections  to  the  use  of  hewed  ties,  and 
these  will  increase  in  importance  in  direct  proportion  to  the  num- 
ber of  ties  treated  with  preservative.  Chief  among  these  objec- 
tions are  (1)  unequal  bearing  afforded  tie  plates  and  rails,  (2), 
lack  of  uniform  volume,  and  (3)  unnecessary  waste  of  valuable 
material. 

Bearing  Afforded  Tie  Plates  and  Rails. —  The  heavy  tonnage 
on  American  railroads  necessitates  the  use  of  some  form  of  tie 
plate  on  practically  all  first-class  construction.  Hewed  ties 
seldom  offer  a  uniform  bearing  surface  to  the  plate  or  rail,  and 


130        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

unless  specially  adzed  before  placement  soon  wear  unevenly  and 
must  be  removed.  An  inspection  of  test  ties  on  the  Chicago 
&  Northwestern  track  showed  in  many  cases  that  one  edge  of  the 
plate  had  cut  into  the  tie  to  a  depth  of  over  1/2  inch,  while 
the  other  edge  was  not  even  flush  with  the  surface.  With  sawed 
ties  the  bearing  over  the  surface  is  more  uniform  and  rail  cutting 
is  considerably  reduced.  The  introduction  of  tie-boring  and 
adzing  machines  is  doing  much  to  improve  the  bearing  of  plates 
on  the  ties  and  should  cut  down  mechanical  wear  appreciably. 

Uniformity  in  Volume. — Since  tie  inspectors  offer  no  objec- 
tion to,  but  rather  favor,  ties  of  greater  dimensions  than  those 
specified,  the  tie  manufacturer  rarely  hews  a  large  log  to  the 
standard  size.  Thus  the  cubic  content  of  hewed  ties  may  vary 
from  that  of  the  uniform  dimensions  allowed  to  about  twice  the 
size  specified.  Practically  all  contracts  for  treating  ties  state 
that  so  much  preservative  shall  be  injected  per  cubic  foot  of 
wood.  With  hewed  ties  no  treating  plant  knows  accurately 
what  this  volume  is  until  after  the  ties  have  been  treated.  To 
obtain  the  total  quantity  of  preservative  to  be  used,  it  is  custom- 
ary to  figure  that  a  tie  will  contain  a  certain  amount  of  wood, 
and  to  multiply  this  figure  by  the  number  of  ties  and  the  amount 
of  preservative  to  be  injected  per  cubic  foot.  For  example,  to 
figure  the  amount  of  creosote  needed  to  treat  1000  cross-ties 
6  inches  by  8  inches  by  8  feet  with  10  pounds  of  oil  per  cubic  foot, 
the  calculation  would  be  1000  X  2.67  X  10  =  26,700  pounds.  If 
the  hewed  ties  average  3.2  cubic  feet,  though  figured  as  of 
standard  size,  the  total  amount  of  preservative  would  be  the 
same,  viz.,  26,700  pounds,  but  the  amount  per  cubic  foot  would  be 
only  8.3  pounds  instead  of  10,  as  specified.  Sawed  ties  are  cut  to 
more  exact  dimensions,  and  errors  of  this  kind  are  improbable. 

Waste  of  Material. — To  hew  a  tie  necessarily  entails  an  enor- 
mous waste  of  material.  Based  on  actual  field  data  the  waste 
by  hewing  varies  from  25  to  75  percent1  (Fig.  17).  Logs  15 
inches  in  diameter  furnish,  as  a  rule,  only  one  hewed  tie,  but  if 
sawed  they  furnish  two.  Whenever  possible  the  tie  hewer  selects 
trees  of  about  12  or  14  inches  in  diameter.  The  waste  of  wood 
each  year  in  the  United  States  from  hewing  ties  amounts  to  about 
285,000,000  cubic  feet,  a  quantity  equivalent  to  about  80  percent 
of  the  total  amount  of  pulpwood  used  in  the  United  States  in 

1  U.  S.  Forest  Service  Bulletin  64,  "Loblolly  Pine  in  Eastern  Texas,  with 
Special  Reference  to  the  Production  of  Cross-ties,"  by  Raphael  Zon. 


PROLONGING  THE  LIFE  OF  CROSS-TIES 


131 


1909.     This  is  an  absolute  waste,  as  it  is  not  even  used  for  fuel. 
(See  Plate  XIII,  Fig.  A.) 

Form  of  Cross-ties. — Practically  all  of  the  wooden  cross-ties 
now  used  on  steam  railroads  in  the  United  States  are  rectangular 
in  cross  section.  Tfeeir  size  is  by  no  means  uniform,  varying  in 
width  from  6  to  10  inches,  in  depth  from  6  to  7  inches,  and  in 
length  from  8  to  9  feet.  These  ties  are  sometimes  cut  either  with 
a  saw  or  axe  on  all  four  sides  (see  Plate  XIII,  Fig.  B),  in  which 
case  they  are  said  to  be  "squared."  In  many  cases  only  the  top 
and  bottom  are  cut,  leaving  the  sides  the  natural  shape  of  the  tree. 
When  thus  made  from  small  trees  the  ties  are  called  "pole  ties." 
In  Europe  a  large  number  of  ties  are  cut  larger  on  the  base  than 
on  the  top  and  are  commonly  referred  to  as  "half-round  ties." 


_^  Boards 
CH  and  Tie 


w-kerMEdgings 


FIG.  17. — Ideal  economy  in  manufacturing  a  cross  tie.  A  =  tie  6  X  8 
inches;  B  =  board  7  inches  wide;  C.  C.  =  boards  5  1/2  inches  wide;  D  = 
board  91/2  inches  wide;  E  =  board  71/2  inches  wide;  F  =  board  3  inches 
wide.  (Diagram  courtesy  of  the  Forest  Service.) 

Such  ties  are  also  used  to  a  limited  extent  in  our  country.  (See 
Plate  XIII,  Fig.  C.)  One  railroad  uses  a  form  of  tie  which  will 
economize  in  timber  by  cutting  them  triangular.  (See  Plate 
XIII,  Fig.  D.)  It  is  believed  that  the  form  of  cross-ties,  especially 
as  regards  the  distribution  of  the  sapwood  on  them,  is  very  im- 
portant and  an  item  too  frequently  overlooked  in  track  con- 
struction. It  is  just  as  logical  to  specify  how  ties  to  be  treated 
shall  be  sawed  or  hewed  as  regards  their  sapwood  'content  and 
its  distribution,  as  it  is  to  specify  a  difference  in  price  due  to 
a  difference  in  the  kind  of  wood.  Exceptions  of  course  occur, 
as,  for  example,  in  those  ties  whose  heartwood  treats  as  easily 


132        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


as  the  sapwood.  Sapwood  is  easy  to  impregnate  with  pre- 
servatives, while  the  heartwood  is  generally  very  resistant. 
This  difference  in  the  resistance  to  treatment  between  the  sap 
and  heartwood  of  the  same  tie  is  often  very  much  greater  than 
the  difference  in  treatment  between  two  ties  of  widely  different 
varieties  of  wood.  In  certain  species  like  the  red  oak,  hemlock, 
and  the  ash,  this  condition  is  not  true,  but  in  the  majority  of  cases 
it  is.  With  most  ties  composed  of  part  heart  and  part  sapwood, 
when  placed  in  a  cylinder  and  injected  with  a  preservative,  most, 
if  not  practically  all  of  the  preservative  will  go  into  the  sapwood. 

A  B 


D 


E 


FIG.  18. — Showing  the  character  of  the  preservative  treatment  in  ties  prop- 
erly and  improperly  manufactured. 

To  secure  best  results  it  is  of  considerable  importance,  therefore, 
to  specify  how  this  sapwood  should  be  distributed.  The  best 
kind  of  cross-tie  intended  for  treatment  is  one  which  has  a  uniform 
distribution  of  sapwood  on  all  surfaces  (Fig.  18  C).  A  tie  of 
this  kind  can  be  very  efficiently  protected  against  decay.  Un- 
fortunately, only  a  comparatively  small  number  of  ties  are  of 
this  kind,  and  even  those  that  are,  are  usually  of  low  crushing 
strength.  By  far  the  largest  percentage  of  ties  now  used  are 
composed  mostly  of  heartwood  or  needless  sapwood,  as  shown  in 
Fig.  ISA  and  Fig.  18  B .  When  ties  of  this  kind  are  treated  accord- 
ing to  the  ordinary  run  of  specifications,  practically  all  of  the 


PLATE  XIII 


FIG.  A. — Method  of  hewing  oak  ties  in  Tennessee.     Note  waste.     (Forest 

Service  photo.) 


r  mm^ 
*  m      i  i 


FIG.  B. — Rectangular  cross-ties — standard  form  in  the  United  States. 

(Facing  page  132.) 


PLATE  XIII 


FIG.  C. — Standard  Prussian  ties  of  Baltic  pine.     (Forest   Service   photo.) 


FIG.  D. — Triangular    cross-ties — Great     Northern     Ry.     (Forest    Service 

photo.) 


PROLONGING  THE  LIFE  OF  CROSS-TIES  133 

preservative  will  go  into  the  sap  wood,  leaving  the  heart  faces  with 
only  a  superficial  penetration.  The  greatest  wear  on  a  tie  comes 
on  its  face  immediately  under  the  rail  or  plate.  This  is  the  por- 
tion which  should  have  the  g«eatest  and  not  the  least  protection 
against  decay,  as  now  generally  occurs  due  to  the  present  methods 
of  manufacture.  If  ties  of  the  type  shown  in  Fig.  ISA  and  Fig. 
18  B  are  treated,  they  can  unquestionably  be  made  to  absorb  the 
amount  of  preservative  specified — say  10  pounds  per  cubic  foot — 
but  most  of  the  preservative  will  be  in  those  portions  of  the  tie 
where  it  will  do  the  least  good.  If,  now,  these  ties  were  sawed 
as  indicated  by  the  dotted  lines  in  the  sketch,  it  would  be  possible 
to  secure  just  as  long  a  life  from  them  with  a  much  less  consump- 
tion of  preservative. 

For  example,  consider  a  modern  treating  plant  having  an 
output  of  approximately  800,000  ties  per  year :  If  the  ties  are  im- 
pregnated with  10  pounds  of  creosote  per  cubic  foot,  the  oil  cost- 
ing 6  cents  per  gallon  and  the  ties  containing  approximately  3 
cubic  feet,  the  total  amount  of  the  oil  used  would  be  approxi- 
mately 24,000,000  pounds.  If,  now,  the  ties  had  been  cut  as  indi- 
cated in  the  sketch,  it  would  be  possible  with  a  consumption  of 
about  6  pounds  of  creosote  per  cubic  foot  to  protect  them  as 
effectively  as  with  10  pounds  in  the  former  case.  This  would 
result  in  a  net  saving  of  approximately  4  pounds  per  cubic  foot 
or  12  pounds  per  tie,  equivalent  to  about  9  cents  per  tie  for  cost 
of  preservative,  or  $72,000  in  one  year's  operation. 

There  are  other  ways  in  which  this  point  could  be  argued. 
For  example,  if  this  unnecessary  sapwood  were  removed,  could 
not  the  life  of  the  tie  be  increased  over  what  it  would  have  been, 
provided  the  quantity  of  oil  injected  in  both  cases  remained  the 
same?  A  company  would  be  justified  in  paying  more  for  prop- 
erly sawed  ties  intended  for  treatment  than  for  ties  which  are 
improperly  sawed  or  hewed,  especially  when  the  treatment  is  one 
using  straight  coal-tar  creosote.  It  is  the  author's  opinion  that 
roads  using  this  method  of  treatment  could  very  well  afford  to 
insert  another  clause  in  their  specifications  for  cross-ties,  concern- 
ing the  amount  and  distribution  of  sapwood,  and  even  go  to  the 
extent  of  paying  a  higher  price  for  ties  in  which  the  sapwood  was 
properly  distributed.  They  would  thereby  save  an  appreciable 
item  in  the  cost  of  treatment.  The  roads  which  do  not  use 
treated  ties  or  which  adhere  to  a  zinc  treatment  would  not  be 
benefited  to  the  same  degree  by  a  requirement  of  this  kind. 


134        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


Such  procedure  would  simply  be  a  step  in  advancing  the  increased 
efficiency  with  which  cross-ties  can  be  utilized,  with  a  view  to 
decreased  cost  in  track  maintenance  and  operation.  The  diffi- 
culties in  putting  it  into  practical  use  would,  in  some  cases,  be 
unsurmountable,  but  where  conditions  of  production  are  such 
that  a  requirement  of  this  kind  could  be  employed,  it  is  believed 
its  adoption  would  unquestionably  result  in  decided  profit. 

In  Fig.  18,  A,  B,  and  C.  represent  the  cross  sections  of  three 
ties,  the  shaded  portion  being  sapwood  and  the  white,  heart- 


The  EiTect  of  Form  of  Pile 

upon 

Rate  of  Seasoning 
SolidPile9x9 
Opeu  Pile?  x  2 


\ 


\ 


2      9     16    23    30     7     14    21    28     4     11    18    25     1     8     15 

June  July  August  September 

Time-Weets 

FIG.  19. — Effect  of  the  form  of  piling  upon  the  rate  of  seasoning  of  lodge- 
pole-pine  ties. 

wood.     The  dotted  lines  show  how  these  ties  could  be  improved 
by  slabbing  the  sides. 

If  impregnated  with  creosote,  the  ties  would  appear  as  in  Figs. 
18  D,  E,  and  F.  Note  the  heavy  impregnation  on  the  sides  and 
the  very  slight  impregnation  on  the  faces  in  Figs.  18  D  and  E. 
Figs.  18  G  and  H  show  ties  A  and  B  slabbed  on  the  sides  and  then 
impregnated  with  creosote.  Note  the  even  distribution  of  the 
preservative  and  the  heavier  injection  on  the  faces  than  in  D  and 
E,  thereby  giving  greater  protection  to  the  tie  where  it  is  most 
needed  and  at  the  same  time  consuming  less  of  the  preservative. 

Stacking  Ties  for  Seasoning. — Different  kinds  of  wood  and 
climate  require  different  methods  of  piling.     The  closer  the  ties 


PROLONGING  THE  LIFE  OF  CROSS-TIES  135 

are  piled  the  slower  will  be  their  loss  in  weight.  In  no  case  should 
more  than  two  ties  in  a  pile  come  in  contact  with  the  ground. 
The  most  open  form  is  th$  triangular  one,  which  can  be  rapidly 
made  and  is  -well  adapted  ^pr  use  along  the  right  of  way.  It 
should  not,  however,  be  used  for  many  hardwoods  cut  in  summer, 
since  these  will  check  badly.  Good  forms  of  piles  are  the  7  by  2, 
7  by  1,  and  8  by  1.  (See  Plate  XIV,  Fig.  A.)  These  are  well 
adapted  for  softwoods  and  for  most  hardwoods  cut  in  summer. 
They  are  easy  to  build  and  permit  of  free  circulation  of  air. 
When  it  is  desired  somewhat  to  retard  the  rate  of  drying,  the  8 
by  2  or  the  10  by  1  form  should  be  used,  or  if  these  are  still  too 
open,  the  7  by  7  form.  An  advantage  of  the  7  by  1,  8  by  1,  10 
by  1,  and  similar  forms  is  that  no  tie  lies  flat  on  another,  thus 
giving  an  easy  run-off  for  rain  water  and  a- free  circulation  of 
air.  In  practically  no  case  should  untreated  ties  be  piled  solidly 
9  by  9,  since  such  forms  are  exceedingly  inefficient  in  regard 
to  seasoning  and  invite  decay.  The  effect  of  the  form  of  piling 
upon  the  rate  of  seasoning  is  shown  in  Fig.  19. 

Though  the  U.  S.  Forest  Service  has  made  many  tests  to  de- 
termine the  effect  of  different  forms  of  roofs  on  the  seasoning  of 
ties,  the  data  secured  are  not  conclusive.  However,  a  slanting 
roof  of  ties  is  fairly  efficient  in  shedding  water,  and  when  not  re- 
quiring too  much  additional  labor  can  be  employed  advantage- 
ously. 

Ties  cut  from  conifers  are  less  likely  to  check  during  seasoning 
than  ties  cut  from  broadleaf  trees,  and  in  consequence  can  be 
piled  more  openly. 

If  ties  are  seasoning  too  fast  they  should  be  piled  closer  to- 
gether (see  Plate  XIV,  Fig.  B) ;  if  seasoning  too  slowly  they  should 
be  piled  more  openly.  Ties  cut  in  winter  can  be  piled  more 
openly  without  danger  of  checking  than  ties  cut  in  summer. 

The  length  of  time  ties  should  season  before  treatment  will 
vary  primarily  with  the  species  of  wood,  form  of  pile,  and  period 
of  the  year.  In  general,  ties  cut  in  spring  and  summer  will  be 
seasoned  sufficiently  for  treatment  by  the  end  of  the  following 
autumn;  ties  cut  in  early  spring  will  be  seasoned  sufficiently  by 
the  following  early  autumn;  the  seasoning  period  varying  from 
about  2  to  4  months.  Ties  cut  in  autumn  and  winter  will  be 
sufficiently  seasoned  by  the  end  of  the  following  spring,  the  period 
varying  from  about  5  to  8  months.  The  periods  necessary 


136        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


to  season  dense  ties  like  the  oaks  will  generally  be  from  2  to 
3  months  longer  than  those  just  given. 

Figs.  20  and  21  illustrate  these  conditions;  Fig.  20  representing 
red  gum  ties  which  season  very  rapidly  and  Fig.  21  red  oak  ties 


Mar.  AJ.P.  May  Jun.  Jul.  Auj.Sept.  Oct.  NOT.  Dec.  Jan.  Feb.  Mar.  Apr.  May  Jun.  Jul.  Auj. 

Time-Months 

FIG.  20. — Rate  of  seasoning  of  red  gum  ties. 


180 
175 
170 
glG5 

fe  IGO 

JS  155 
ij 

•S  m 
|  145 
140 

135 
130 
125 

•2 

0 

•" 

c^ 

5 

1 

A 

1 

-=h 

, 

4 

1 

\ 

M 

\ 

\ 

1 

x 

\ 

3 

o 

\ 

V 

Mi 

\ 

\ 

^ 

\ 

\ 

,% 

6 

^V 

% 

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\ 

ri. 

HI 

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i--^. 

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TT- 

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K"o, 

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5 

* 

Mar.   Apr.  May  Jun.  Jul.  Aug.  Sept.  Oct.  NOT.  Dec.  Jan.   Feb.  Mar.  Apr.  May  Jun.  JuU  Aug. 

Time-Months 

FIG.  21. — Rate  of  seasoning  of  red  oak  ties. 

which  season  slowly.     Both  figures  show  the  accelerated  drying 
in  the  warmer  months  and  the  retarding  action  of  winter. 

Grouping  Ties  to  Secure  Uniform  Treatment. — The  importance 
of  properly  grouping  ties  before  placing  them  in  the  treating 


PROLONGING  THE  LIFE  OF  CROSS-TIES  137 

cylinder  cannot  be  overemphasized.  If  ties  offering  unequal 
resistance  to  penetration  are  treated  at  the  same  time,  those 
offering  the  greatest  resistance  will  take  practically  no  pre- 
servative, while  the  others  ^ill  get  it  all.  Consequently,  if  ties 
so  treated  areplacecl  in  a  roadbed,  the  ones  heavily  injected  will 
outlast  the  others  and  the  wear  on  the  track  will  not  be  uniform. 
Furthermore,  when  the  ties  inadequately  treated  decay,  the  load 
which  should  be  borne  by  them  will  be  transferred  to  the  sound 
ones,  hastening  their  mechanical  destruction.  Thus  much  of  the 
preservative  will  be  wasted,  since  there  is  no  economy  in  pre- 
serving ties  from  decay  after  they  have  been  worn  out.  The 
aim,  therefore,  should  be  to  have  the  ties  depreciate  uniformly, 
and  this  can  largely  be  brought  about  by  grouping  them  in  such 
a  manner  that  they  will  receive  equal  amounts  of  the  preservative 
uniformly  diffused.  Many  tie  plants  already  realize  the  import- 
ance of  grouping,  and  consider  the  added  expense  more  than  justi- 
fied by  the  results  secured. 

The  chief  factors  which  determine  the  ease  with  which  ties 
may  be  impregnated  are  (1)  the  species  of  wood,  (2)  percent  of 
sap  and  heartwood,  (3)  moisture  content.  The  less  important 
are  conditions  under  which  seasoned,  time  of  cutting,  and  con- 
ditions of  growth. 

Species  of  Wood. — It  has  been  explained  in  Chapter  III  that 
the  species  of  wood  differ  greatly  in  their  physical  properties  and 
that  this  difference  accounts  in  a  large  measure  for  the  variable 
results  secured  in  preservative  treatments. 

Interesting  experiments  on  20,000  ties  to  ascertain  the  absorp- 
tive properties  were  made  by  Mr.  F.  J.  Angier  in  1908-09  at  the 
treating  plant  of  the  Chicago,  Burlington  &  Quincy  Railroad, 
using  the  zinc-creosote  process.  The  results  are  summarized 
in  Table  9. 

Class  A  includes  ties  absorbing  less  than  22  percent  of  their 
volume;  Class  B,  ties  absorbing  between  23  and  30  percent; 
Class  C,  ties  absorbing  more  than  30  percent.  In  all  cases  the 
ties  were  kept  in  the  cylinder  until  no  more  preservative  could  be 
forced  into  them.  With  hardwoods,  such  as  oak,  hickory,  ash, 
beech,  etc.,  the  pressure  was  175  pounds,  but  with  softwoods 
this  was  reduced  to  from  125  to  150  pounds  per  square  inch.  In 
both  cases  the  pressure  was  held  for  from  2  to  5  hours.  No  sepa- 
ration of  the  ties  was  made  on  the  basis  of  their  proportion  of  sap- 
wood  and  heartwood,  but  about  75  percent  of  them  were  hewed. 


138        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

TABLE  9. — ABSORPTION  OF  PRESERVATIVE  BY  VARIOUS  SPECIES  OF 
CROSS-TIES1 

CLASS  A 


Kind  of  wood 

Number 
ties  used 
in  the  tests 

Absorption 
percent 
of  volume 

Number 
months 
seasoned 
in  yard 

Beech 

2,481 

21  8 

15 

Oak,  red  

3,112 

20  9 

6-15 

Hemlock 

1,364 

20  7 

8-15 

Oak  pin 

671 

19  5 

10 

Hickory  '  

414 

18  8 

2-  8 

Tamarack 

2,329 

17  1 

6-  8 

Oak,  white  

731 

14.2 

7 

CLASS  B 

Hard  maple 

691 

28  3 

15 

Popular 

1  348 

26  8 

7-  9 

Sycamore                                     

364 

26  6 

7 

Ash 

318 

23  0 

2-  6 

Sweet  gum  

928 

23.0 

5-  9 

Chestnut 

345 

22  6 

12 

CLASS  C 

Shortleaf  pine  
White  elm 

2,192 

872 

36.9 
36  6 

5-  9 
7-15 

Cypress,  white 

662 

35  4 

7-  8 

Red  elm  ...                                   

626 

34.9 

6-  9 

Soft  maple 

599 

33  1 

6 

Red  birch  

775 

33.0 

6-  9 

Tupelo  gum  

790 

30.7 

8 

Proportion  of  Sapwood. — As  has  been  stated,  the  sapwood  of 
practically  all  woods  native  to  the  United  States  readily  absorbs 
preservatives.  The  heartwood,  however,  is  much  more  resistant, 
so  much  so  in  some  cases  that  no  effective  treatment  is  possible. 
Two  hundred  maple  ties  thoroughly  air  seasoned  (the  moisture 
content  ranging  from  24  to  39  percent)  were  treated  by  the  full- 
cell  and  Burnett  processes  at  the  U.  S.  Forest  Products  Labora- 
tory. It  was  found  that  of  the  ties  given  a  full-cell  treatment, 
those  containing  43.7  percent  sapwood  absorbed  10.48  pounds  of 
creosote  per  cubic  foot,  while  those  containing  82.7  percent  of 
sapwood  absorbed  17.40  pounds  per  cubic  foot.  In  the  Burnett 
treatments  the  difference  was  not  so  pronounced.  Ties  contain- 
ing 46.2  percent  sapwood  absorbed  19.7  pounds  of  solution, 


1  Proceedings  of  Wood  Preserver's  Assn.,  1911 


PROLONGING  THE  LIFE  OF  CROSS-TIES 


139 


while  those  which  contained  80.5  percent  absorbed  22.5  pounds. 
Because  of  this  difference  in  the  absorption  by  sapwood  and 
heartwood,  ties  which  contain  large  amounts  of  sapwood  should 
be  treated  separately.  Diff $rences  in  absorption  by  ties  of  the 
same  species,  but  with  varying  proportions  of  sapwood,  are 
often  greater  than  in  the  case  of  widely  different  species.  If  the 
ties  are  "  pole  "ties,  it  will  be  found  that  those  of  certain  species 
almost  invariably  fall  in  the  same  class  when  graded  with  refer- 
ence to  the  percent  of  sapwood.  The  grouping  will  be  approx- 
imately as  shown  in  Table  10. 

TABLE    10. — CLASSIFICATION    OP    POLE   TIES  BASED  ON  THEIR  SAPWOOD 

CONTENT 


Group  I 
Sapwood  1  inch  or  less  in 
width  (less  than   20   per 
cent  of  volume  of  tie) 

Group  11 
Sapwood  1  inch  to  2j  inches 
in  width  (more  than  20  per- 
cent, but  less  than  50  per- 
cent of  volume  of  tie) 

Group  III 
Sapwood  over  3  inches  wide 
(more  than  50  percent  of 
volume  of  tie) 

Oaks. 

Longleaf  pine. 

Shortleaf  pine. 

Douglas  fir. 

White  pine. 

Loblolly  pine. 

Cedar. 

Hard  maple. 

Western  yellow  pine. 

Chestnut. 

White  elm. 

Cypress. 

Tamarack. 

Red  elm. 

Lodgepole  pine. 

Hemlock. 

Tupelo  gum. 

Spruce. 

Red  gum. 

Sycamore 

Poplar. 

Soft  maple. 

Red  birch. 

Hickory. 

Ash. 

! 

Beech. 

This  grouping  does  not,  however,  in  all  cases  accurately  rep- 
resent the  relative  resistance  to  penetration  of  the  various 
species.  For  example,  red  oak,  because  of  its  porous  nature, 
can  readily  be  penetrated  to  the  center,  and  thus,  in  spite  of  its 
comparatively  small  amount  of  sapwood,  would  be  grouped  with 
ties  of  a  structure  resembling  the  elms.  Also,  the  sapwood  of 
soft  maple,  hickory,  ash,  and  beech  is  more  resistant  to  treatment 
than  that  of  the  other  species  mentioned  in  Group  III. 

If  ties  are  cut  from  logs  larger  than  12  to  14  inches  in  diameter, 
as  is  usually  the  case  with  sawed  ties,  the  percentage  of  sapwood 
may  range  from  zero  to  the  maximum  shown  in  the  table;  hence 
the  grouping  of  such  ties  may  be  different  from  that  given.  For 


140        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

example,  shortleaf  pine  ties  cut  with  little  or  no  sap  wood  would  fall 
in  Group  II,  hard  maple  without  sapwood  in  Group  I.  Sapwood 
can  be  distinguished  from  heartwood  by  its  difference  in  color,  and 
it  is  as  a  rule  easy  to  separate  ties  into  groups  according  to  their 
sapwood  content.  Such  a  separation  will  undoubtedly  assist 
in  a  pioper  grouping  of  ties  for  treatment,  but  before  this  group- 
ing can  definitely  be  decided  upon  as  the  best,  considerably  more 
experimenting  will  be  necessary. 

Moisture  Content. — When  ties  are  green  the  tjell  walls  and 
many  of  che  cell  spaces  are  filled  with  water.  To  properly  inject 
a  preservative,  at  least  a  part  of  this  water  must  be  removed,  and 
the  extent  to  which  it  has  been  removed  governs  the  amount  of 
preservative  which  can  be  injected.  It  is  important,  therefore, 
that  all  of  the  ties  to  be  treated  at  one  time  should  have  approxi- 
mately the  same  moisture  content.  One  of  the  most  practical 
ways  of  insuring  this  is  to  pile  the  ties  in  the  yard  and  thoroughly 
air-season  them. 

The  conditions  under  which  ties  season  effect  the  uniformity 
of  the  treatment.  Ties  seasoned  too  rapidly  are  likely  to  "  case- 
harden,"  which  makes  them  more  difficult  to  impregnate  and 
affects  their  strength.  Moreover,  whether  ties  are  seasoned  with 
the  bark  on  or  off  affects  the  treatment.  It  is  good  practice  to 
season  all  ties  to  be  treated  in  one  charge  under  the  same  condi- 
tions. 

Cutting  Season. — The  time  of  year  the  ties  are  cut  also  affects 
the  uniformity  and  degree  of  treatment.  Several  tramloads  of 
hemlock  ties  cut  in  the  summer,  fall,  and  winter  were  first  air- 
seasoned  and  then  treated  with  zinc  chloride,  with  the  results 
shown  in  Table  11. 

TABLE  11. — EFFECT  OF  THE  SEASON  OF  CUTTING  ON  THE  AB- 
SORPTION OF  PRESERVATIVE 


Weight  per  cubic  foot 
before  treatment 

Average  absorption  of 
solution  per  cubic  foot 

Summer  

Pounds 
33.4 

Pounds 
12.9 

Fall  
Winter  

36.2 
37.3 

10.0 

8.9 

It  is  probably  safe  to  say  that,  aside  from  moisture  content  and 
case-hardening,  the  effect  of  the  time  of  cutting  on  the  penetra- 
tion and  absorption  of  preservative  can  be  neglected  in  commercial 


PROLONGING  THE  LIFE  OF  CROSS-TIES  141 

work.  Good  practice  consists  in  cutting  all  ties  in  winter  or  late 
fall  whenever  possible. 

Conditions  of  Growth.—Tlie  arrangement  of  the  cells  in  the 
same  species  of  wood  grown  under  different  conditions  may  differ 
to  such  an  extent  as  to  cause  variability  in  the  results  of  the  treat- 
ment. When  that  is  the  case,  the  ties  should  be  grouped  sepa- 
rately. For  example,  a  plant  receiving  red  oak  ties  from  the 
South  may  find  it  advantageous  to  group  them  separately  from 
those  received  from  the  North.  Moreover,  ties  cut  from  various 
parts  of  the  tree  treat  differently. 

Although  the  above  considerations  sound  very  complicated, 
they  are  not  difficult  of  practical  execution.  It  goes  without  say- 
ing that  the  careful  grouping  of  ties  for  treatment  costs  more 
than  not  grouping  them,  but  there  is  no  doubt  but  what  it  will 
far  more  than  pay  in  the  long  run.  This  is  particularly  true  for 
treatments  with  creosote  where  the  amount  of  preservative 
forced  into  the  ties  is  not  the  maximum  amount  they  will  absorb 
but  the  amount  called  for  by  the  specification.  Grouping  is 
least  essential  when  the  ties  are  impregnated  with  a  solution  of 
zinc  chloride,  which  can  be  forced  into  them  until  there  is  no 
more  absorbed  or  until  the  point  of  refusal  is  reached. 

Protection  from  Abrasion. — It  has  been  estimated  that  from 
10  to  75  percent  of  unprotected  ties  fail  by  rail  and  spike  cutting;1 
the  former  figure  referring  to  hard,  quick-decaying  ties  like  maple, 
the  latter  to  durable,  soft  ties  like  cedar.  Since  the  number  of 
treated  ties  is  increasing  annually,  this  percentage  will  also  in- 
crease rapidly  unless  improved  methods  of  fastening  rails  are 
generally  adopted.  Already  the  amount  of  preservative  injected 
into  ties  is  in  some  cases  reduced  because  it  is  claimed  to  be  more 
than  is  necessary  to  prevent  decay  throughout  their  mechanical 
life.  With  increased  mechanical  life  of  the  tie  the  efficiency  of 
the  preservative  treatment  may  also  be  increased. 

The  most  practical  means  of  reducing  the  mechanical  de- 
struction of  ties  are  through  the  use  of  tie-plates  and  improved 
forms  of  spikes. 

Tie -Plates. — Tie-plates  are  designed  primarily  to  (1)  distribute 
the  impact  and  compression  of  trains  over  the  tie;  and  (2)  absorb 
the  grinding  action  of  the  rail. 

If  the  tie-plate  is  too  light  it  will  soon  buckle,  or  if  its  bearing 
surface  is  too  small  it  will  become  embedded  in  the  tie.  In 

1  Proceedings  A.  R.  E.  and  M.  of  W.  Association,  Vol.  9,  1908. 


142        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

either  case  the  value  of  the  plate  is  reduced.  It  is  essential,  there- 
fore, to  use  plates  that  are  strong  enough  to  stand  the  pressure 
exerted  on  them,  and  that  have  sufficient  surface  area  to  properly 
distribute  the  load.  Failure  to  meet  these  conditions  will  al- 
most invariably  result  in  severe  mechanical  wear  on  the  tie.  This 
is  shown  in  Plate  III,  Fig.  A. 

Many  forms  of  tie-plates  are  now  on  the  market,  but  in  general 
plates  may  be  divided  into  two  groups:1  (1)  Pronged  or  ridged 
plates;  (2)  flat  plates. 

In  the  opinion  of  some  engineers  the  tie-plates  should  be  so 
firmly  fastened  to  the  tie  that  they  really  become  part  of  it. 
To  secure  this  condition,  the  bottom  of  the  plate  is  pronged, 
ridged,  or  flanged.  (See  Plate  XIV,  Fig.  D.)  Plates  of  this  type 
were  used  in  test  ties  on  the  Northern  Pacific  and  Chicago  and 
Northwestern  experimental  tracks  laid  in  cooperation  with  the 
U.  S.  Forest  Service.  Although  they  have  not  been  in  service  long 
enough  to  show  their  real  worth,  the  following  points  were  observed 
during  recent  inspections.  When  the  plates  are  heavily  ridged,  it 
takes  a  very  heavy  load  to  embed  the  ridges  and  bring  the  plates 
down  flush  with  the  tie.  In  the  Chicago  and  Northwestern  track, 
even  after  2  years'  service,  the  majority  of  the  ridged  plates  were 
elevated  about  1/4  inch  above  the  tie.  This  was  due  in  part  to 
the  resistance  offered  by  the  ridges  to  embedment  in  the  wood 
and  in  part  to  sand  and  gravel  which  collected  under  the  plate; 
also,  to  the  fact  that  the  traffic  over  this  portion  of  the  track  is 
now  very  light.  After  these  plates  become  firmly  embedded  they 
have  a  tendency  to  split  open  the  ties,  and  thus  not  only  weaken 
them,  but  furnish  catch  basins  for  the  retention  of  rain  water. 
In  ties  which  are  difficult  to  impregnate  with  preservatives,  these 
checks  may  extend  beyond  the  zone  of  treated  wood  and  thus 
expose  the  untreated  interior  of  the  tie  to  decay.  Another  char- 

1  Wooden  plates  have  also  been  used  experimentally,  and  are  being  tested 
by  the  U.  S.  Forest  Service  in  both  the  Chicago  and  Northwestern  and 
Northern  Pacific  tracks.  The  plates  are  made  of  creosoted  oak  and  maple, 
about  five-eighths  of  an  inch  thick,  8  inches  long,  and  as  wide  as  the  base  of  the 
rail.  They  are  inserted  between  the  tie  and  the  rail  without  any  previous 
adzing,  the  common  practice  abroad.  The  results  thus  far  have  been 
that  the  plates  split  badly,  and  at  times  have  become  loose  or  displaced. 
In  some  cases  they  have  embedded  themselves  into  the  ties.  This  is  shown 
in  Plate  XIV,  Fig.  C.  Although  the  tests  with  wooden  plates  have  not  as 
yet  been  completed,  the  results  thus  far  secured  have  not  been  satis- 
factory. It  is  thought,  however,  that  this  is  largely  due  to  the  poor 
manner  in  which  they  were  placed. 


PLATE  XIV 


FIG.  A. — A  good  method  of  piling  ties  for  air  seasoning,  Port  Reading 
Creosoting  Co.     (Forest  Service  photo.) 


FIG.  B. — White-oak  ties  seasoned  too  fast. 


(Forest  Service  photo.) 
(Facing  page  142.) 


PLATE  XIV 


FIG.  C. — Ties  "protected"  with  wooden  plates.     Note  plate  crushed  into 
tie.     (Forest  Service  photo.) 


FIG.  D. — Metal  tie  plate.     (Courtesy  Spencer-Otis  Mfg.  Co.) 


PROLONGING  THE  LIFE  OF  CROSS-TIES  143 

acteristic  of  such  plates  is  to  grind  into  the  wood  fibers,  especially 
of  softwood  ties  such  as  loblolly  pine,  cedar,  etc.  This  action 
also  may  extend  beyond  the  treated  portions  of  the  tie  and  cause 
interior  rot.  These  features  are  unquestionably  objectionable, 
and  in  some  cases  may  prove^)f  such  a  serious  nature  that  they 
will  overbalance  the  good  points,  such  as  adherence  to  the  tie 
and  lack  of  rattling,  claimed  for  plates  of  this  type. 

The  objectionable  features  of  pronged  or  flanged  plates  are 
obviated  if  they  are  made  flat  and  so  rest  flush  on  the  surface  of 
the  tie.  The  chief  objections  to  this  type  seem  to  be  the  rattling 
noise  which  they  make  when  they  are  not  firmly  held  to  the  spikes, 
and  the  fact  that  all  resistance  to  creeping  and  lateral  thrust 
must  be  borne  entirely  by  the  spikes.  The  rattling,  however, 
would  seem  to  be  an  excellent  indication  that  the  spikes  are  loose 
and  need  attention.  Just  how  much  weight  must  be  attached 
to  the  second  objection  cannot  at  this  time  be  ascertained  from 
the  plates  under  observation  by  the  U.  S.  Forest  Service.  Thus 
far  no  creeping  or  widening  of  the  gauge  of  the  experimental  track 
has  been  noticed. 

It  seems,  moreover,  in  view  of  the  data  thus  far  secured,  that 
of  the  various  forms  of  tie-plates  now  under  test,  those  made 
of  metal  with  a  flat  bearing  surface,  or  the  bearing  surface  only 
slightly  ridged,  are  giving  better  service  in  protecting  the  ties 
from  mechanical  destruction  than  those  made  of  metal  heavily 
flanged  or  pronged. 

A  feature  which  is  not  a  present  taken  into  account,  but  which 
unquestionably  will  be,  is  the  size  of  tie-plate  to  be  used  on 
different  kinds  of  wood.  A  softwood  tie  like  loblolly  pine  is  more 
subject  to  rail  cutting  than  a  hardwood  tie  like  oak,  and  con- 
sequently needs  a  larger  tie-plate  for  its  protection.  Some  tests 
at  the  U.  S.  Forest  Products  Laboratory  of  compressive  strength 
of  various  kinds  of  ties  gave  results  as  shown  in  Table  12  on 
pages  144  and  145. 

In  other  words,  shortleaf  pine  is  only  about  half  as  strong  as 
red  oak  and  consequently  needs  a  plate  with  a  considerably 
larger  area  in  order  properly  to  distribute  the  load. 

Spikes. — The  practice  of  spiking  ties  to  the  rail  has  long  been 
recognized  as  capable  of  improvement.  The  spikes,  especially 
in  softwood  ties,  do  not  hold  firmly,  and  permit  the  rail  to  "  creep  " 
and  "pump,"  thus  greatly  shortening  the  life  of  the  tie.  Fur- 
thermore, they  tear  the  wood-fibers,  work  loose,  and  permit  rain 


144        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


TABLE  12. — CRUSHING  STRENGTH  OF  CROSS-TIES  IN  PERCENT  OF    WHITE 

OAK 


Kind  of  tie 

Fiber    stress 
at  elastic 
limit  per- 
pendicular, 
to  grain,  Ib. 
per  sq.  in. 

Fiber  stress 
in  percent 
of  white  oak, 
or   853   Ib. 
per  sq.  in. 

Common  name 

Botanical  name 

Osage  orange  
Honey  locust 

Toxylon  pomif  erum  .... 
Gleditsia  triacanthos  .  .  . 
Robinia  pseudacacia.  .  . 
Quercus  minor  
Hicoria  glabra  
Hicoria  aquatica  

2,260 
1,684 
1,426 
1,148 
1,142 
1,088 
1,070 
1,012 
997 
986 
938 
857 
853 
836 
828 
778 
742 
696 
607 
599 
578 
548 
531 
525 
518 
497 
491 
480 
456 
454 
451 
444 
433 
427 
408 
400 
358 
353 
351 
348 

265.0 
197.5 
167.2 
134.6 
133.9 
127.5 
125.5 
118.6 
116.9 
115.7 
110.0 
100.5 
100.0 
98.0 
97.1 
91.2 
87.0 
81.6 
71.2 
70.2 
67.8 
64.3 
62.3 
61.6 
60.8 
58.3 
57.6 
56.3 
53.5 
53.2 
52.9 
52.1 
50.8 
50.1 
47.8 
46.9 
42.0 
41.4 
41.2 
40.8 

Black  locust  
Post  oak               .... 

Pignut  hickory 

Water  hickory  
Shagbark  hickory  .... 
Mockernut  hickory.... 
Big  shellbark  hickory. 
Bitternut  hickory  .... 
Nutmeg  hickory  
Yellow  oak 

Hicoria  ovata  
Hicoria  alba  

Hicoria  laciniosa  
Hicoria  minima 

Hicoria  myristicaeformis 
Quercus  velutina. 

White  oak  
Bur  oak  
White  ash      

Quercus  alba  

Quercus  macrocarpa.  .  .  . 
Fraxinus  americana  
Quercus  rubera  
Acer  saccharum 

Red  oak  

Sugar  maple  
Rock  elm  
Beech  
Slippery  elm  
Redwood  

Ulmus  
Fagus  atropunicea  
Ulmus  pubescens  

Sequoia  sempervirens  .  .  . 
Taxodium  distichum..  .  . 
Acer  rubrum  

Bald  cypress 

Red  maple  
Ha  ckb  erry 

Celtis  occidentalis 

Incense  cedar  

Libocedrus  decurrens  .  .  . 
Tsuga  canadensis. 

Hemlock 

Longleaf  pine  
Tarn  ara  ck 

Pinus  palustris  
Larix  lariciana 

Silver  maple  
Yellow  birch  
Tupelo  
Black  cherry  
Sycamore  
Douglas  fir  
Cucumber  tree.  .  .  . 

Acer  saccharinum  
Betula  L/utea 

Nyssa  aquatica  

Prunus  serotina  
Platanus  occidentalis..  .  . 
Pseudotsuga  taxifolia  .  .  . 
Magnolia  acuminata.  .  .  . 
Pinus  echinata  
Pinus  resinosa  
Pinus  lambertiana  
Ulmus  americana  

Shortleaf  pine  

Red  pine  

Sugar  pine  
White  elm  
Western  yellow  pine.  . 

Pinus  ponderosa  

PROLONGING  THE  LIFE  OF  CROSS-TIES 


145 


TABLE  12.— CRUSHING  STRENGTH  OF  CROSS-TIES  IN  PERCENT  OF  WHITE 

OAK. — Continued. 


Kind 

of  tie       ij 

•    It 

Fiber  stress 
at  elastic 
limit  per- 

Fiber  stress 
in  percent 

Common  name 

Botanical  name 

pendiculaa, 
to  grain,  Ibs. 
per  sq.  in. 

or  853  Ib. 
per  sq.  in. 

Lodgepole  pine  

Pinus  contorta  

348 

40  8 

Red  spruce          

Picea  rubens  .  . 

345 

40  5 

White  pine  
Engelmann  spruce.  .  . 
ArborvitsB 

Pinus  strobus  
Picea  engelmanni  
Thuja  occidentalis 

314 
290 

288 

36.8 
34.0 
33  8 

Largetooth  aspen.  .  .  . 
White  spruce  
Butternut  

Populus  grandidentata  . 
Picea  canadensis  
Juglans  cinerea  

269 
262 

258 

31.5 
30.7 
30  3 

Buckeye  (yellow)  .... 
Basswood      .    . 

Aesculus  octandra  
Tilia  americana 

210 
209 

24.6 
24  5 

Black  willow 

Salix  nigra 

193     ' 

22  6 

to  collect  and  decay  to  start.  This  necessitates  a  rather  frequent 
respiking  of  the  rail,  which  often  fills  the  tie  with  holes  to  such 
an  extent  that  it  is  " spiked  to  death"  and  must  be  removed. 
It  was  thought  that  by  first  boring  a  hole  into  the  tie  and  then 
driving  the  spike  into  it,  the  fibers  would  not  be  torn  and  then  the 
spike  would  hold  more  firmly.  (See  Plate  XII,  Fig.  C.)  Tests 
were  made1  in  which  ordinary  9/16-inch  square  spikes  were  driv- 
en into  red-oak  ties  previously  bored  with  holes  3/8,  7/16,  and 
1/2  inches  in  diameter.  Although  the  spikes  were  driven  by  an 
experienced  trackman,  in  over  half  the  cases  they  failed  to  follow 
the  holes.  Their  resistance  to  pulling  was  thus  reduced.  When 
no  hole  was  bored  the  average  force  required  to  pull  the  spikes 
was  8827  pounds;  when  bored  in  the  manner  above  described 
the  respective  forces  were  8050,  8106,  and  7154  pounds.  In  order 
to  overcome  the  objection  mentioned  the  spikes  were  pointed  on 
four  sides,  and  when  this  was  done  there  was  no  difficulty  what- 
ever in  getting  them  to  follow  the  holes.  Furthermore,  their 
resistance  to  vertical  pull  was  increased  and  the  wood-fibers 
were  not  seriously  torn.  The  number  of  pounds  required  to  pull 
pikes  from  red-oak  ties  was  as  follows  :2 

1  By  J.  A.  Newlin,  in  charge  of  timber  tests,  Forest  Products  Laboratory. 

2  It  will  be  noticed  that  the  spikes  driven  in  the  first  test  held  more  firmly 
than  those  driven  in  the  second.     For  example,  when  no  hole  was  bored  it 
took  8827  pounds  to  pull  them  in  the  first  test  and  only  7613  pounds  in  the 

10 


146        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Pounds 

Ordinary  9/16-inch  square  spikes  driven  without  boring 7613 

Ordinary  9/16-inch  square  spikes  pointed  on  four  sides,  driven  in 

hole  3/8  inch  in  diameter 8178 

Ordinary  9/  16-inch  square  spike  pointed  on  four  sides,  driven  in 

hole  7/16  inch  in  diameter 7856 

Ordinary  9/16-inch  square  spike  pointed  on  four  sides,  driven  in 

hole  1/2  inch  in  diameter .      7664 

When  the  diamond-pointed  spikes  were  driven  into  the  tie 
without  first  boring  holes,  the  ties  were  almost  invariably  split. 
It  appears,  therefore,  that  they  cannot  be  used  satisfactorily 
without  previous  boring. 

Some  of  the  ties  used  in  these  tests  were  treated  with  creosote, 
others  with  zinc  chloride,  and  still  others  were  left  untreated, 
but  no  appreciable  difference  due  to  treatment  was  noticed. 
In  a  few  cases  a  heavy  oil  was  poured  into  the  holes  and  allowed 
to  soak  for  16  hours  before  the  spikes  were  driven.  The  resist- 
ance to  pull  was  decreased  from  7644  to  6628  pounds.  While  no 
tests  were  made,  it  is  quite  possible  that  if  the  holes  are  bored  into 
the  ties  before  they  are  treated  the  resistance  of  the  spike  will  be 
less  than  if  they  are  bored  after  treating.  In  spite  of  this,  how- 
ever, it  is  believed  that  if  holes  are  bored  at  all  they  should  be 
bored  before  and  not  after  treatment,  since  in  the  former  case  the 
ties  will  be  fully  protected  against  rot. 

While  the  tests  described  show  that  boring  holes  into  ties  pre- 
vious to  spiking  them  is  an  improvement  over  the  common  prac- 
tice in  this  country,  experience  abroad  leads  to  the  conclusion 
that  even  better  results  can  be  obtained  by  the  use  of  screw 
spikes.  To  secure  data  for  American  operating  conditions, 
screw  spikes  were  used  by  the  U.  S.  Forest  Service  in  the  Northern 
Pacific,  Chicago  &  Northwestern,  and  Chicago,  Milwaukee  & 
St.  Paul  test  tracks.  In  laying  the  Northern  Pacific  and  Chicago 
&  Northwestern  tracks  no  screw-spike  boring  or  driving  machine 
was  available,  so  that  the  holes  had  to  be  bored  and  the  spikes  in- 
serted by  hand.  In  some  cases  the  holes  were  not  bored  deep 
enough,  and  the  point  of  the  spike  struck  the  base  of  the  hole. 
On  further  tightening  the  spike  the  threads  in  the  wood  were 
destroyed.  Furthermore,  the  holes  were  not  in  all  cases  bored 

second.  This  cannot  be  attributed  to  any  difference  in  the  spikes,  but  to  the 
ties  into  which  they  were  driven.  Also,  in  the  latter  case  the  spikes  were 
pulled  soon  after  they  were  driven.  The  two  series  of  tests,  therefore,  are  not 
comparable  with  each  other. 


PROLONGING  THE  LIFE  OF  CROSS-TIES  147 

vertically,  so  that  the  spikes  were  inserted  at  various  angles. 
When  the  Chicago,  Milwaukee  &  St.  Paul  track  was  put  in  place, 
a  screw-spike  boring  and  driving  machine  was  used,  and  the 
difficulties  previously  encountered  were  done  away  with.  The 
machine  drove  the  ttoles  vertically  and  to  a  uniform  depth,  so 
that  the  spikes  all  had  proper  alignment  and  clearance.  In 
every  case  the  machine  drove  the  spikes  firmly  into  the  tie. 

The  screw  spikes  used  in  the  Northern  Pacific  and  Chicago  & 
Northwestern  test  tracks  were  driven  through  plates  which  did 
not  reenforce  the  head  of  the  spike  against  lateral  thrust.  After 
3  years'  service  many  of  the  these  spikes  were  badly  bent, 
resulting  in  a  widening  of  the  track  gauge.  In  laying  the  Chicago, 
Milwaukee  &  St.  Paul  track,  a  plate  with  bosses  for  supporting 
the  heads  of  the  spikes  was  used,  which  it  is  believed  will  mate- 
rially increase  their  holding  power. 

In  a  large  number  of  tests  made  at  Purdue  University,  a  part 
of  which  were  conducted  by  the  U.  S.  Forest  Service,1  it  was 
found  that  screw  spikes  had  from  1.7  to  3.8  times  the  strength  of 
the  common  spike  against  pull,  and  from  1.2  to  2.4  times  the  lat- 
eral resistance  of  the  common  spike.  The  heads  of  the  spikes 
were  not  supported  in  these  tests. 

An  objection  raised  against  the  use  of  screw  spikes  is  that  it 
takes  longer  to  insert  them  than  to  insert  cut  spikes,  and  that  this 
at  times  delays  the  passage  of  fast  trains.  In  laying  the  Chicago, 
Milwaukee  &  St.  Paul  test  track  this  objection  was  partially 
overcome  by  spiking  every  third  tie  throughout  the  rail  length, 
which  permitted  trains  to  pass,  and  afterward  spiking  the  re- 
maining ties. 

A  further  objection  to  the  use  of  screw  spikes  is  the  difficulty 
of  regauging  the  track  when  the  rail  becomes  worn.  It  is  pos- 
sible that  this  objection  may  in  time  be  overcome  by  altering  the 
design  of  plates  used  with  this  type  of  spike. 

While  the  use  of  screw  spikes  in  this  country  is  still  in  its  in- 
fancy and  final  judgment  cannot  as  yet  be  pronounced,  it  gives 
promise  of  overcoming  the  objections  raised  against  the  ordinary 
cut  spike.  If  it  succeeds  in  this  it  will  unquestionably  result  in 
greatly  reducing  the  mechanical  destruction  of  ties. 

Adzing  and  Boring  Ties. — In  Chapter  VII  it  was  stated  that 
adzing  and  boring  ties  prior  to  treatment  was  good  practice,  and 

1  Fourth  Progress  Report  of  Tests  on  Treated  Ties,  by  W.  K.  Hatt, 
Purdue  University,  Bulletin  124,  A.  R.  E.  and  M.  of  W.  Assn. 


148        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  data  given  above  show  how  the  holding  power  of  spikes  can 
be  increased  by  driving  them  through  such  holes.  Of  equal 
importance  is  a  proper  bearing  of  the  rail  or  plate  on  the  tie,  for 
if  this  is  not  done  the  wear  will  be  concentrated  over  a  small 
area  and  the  mechanical  destruction  of  the  tie  hastened.  Further- 
more, it  is  felt  that  the  unequal  bearing  of  rails  on  ties  can  be 
held  responsible,  in  part  at  least,  for  breaking  the  rail,  especially 
during  cold  weather.  Adzing  prior  to  treatment  not  only  en- 
ables the  plate  and  rail  to  be  firmly  and  uniformly  fastened  to  the 
tie,  but  makes  it  possible  to  at  least  coat  with  preservative  that 
portion  of  the  tie  most  subject  to  wear.  For  these  reasons 
adzing  and  boring  of  ties  are  highly  commended. 

The  Selection  of  Processes  for  Treating  Ties. — The  wide 
range  of  conditions  under  which  cross-ties  are  used  makes  a 
selection  of  treating  processes  necessary  if  most  economic  results 
are  to  be  secured.  Lack  of  specific  data  on  the  exact  value  of  the 
various  processes  prevents  a  clear-cut  decision  as  to  which  is  best 
for  a  given  set  of  requirements. 

The  ideal  treatment  is  one  in  which  the  ties  fail  from  decay 
and  wear  at  the  same  time.  If  the  failures  are  caused  by  decay, 
then  a  more  efficient  preservative  should  be  used;  if,  on  the  other 
hand,  the  failures  are  caused  by  wear  which  cannot  be  prevented, 
then  a  less  efficient  treatment  should  be  used.  It  can  be  readily 
seen  that  any  process  which  puts  into  ties  more  preservative 
than  is  necessary  to  protect  them  longer  than  their  mechanical 
life  is  a  wasteful  process,  because  after  the  ties  are  removed  from 
the  track  the  preservative  in  them  is  useless.  The  proper  balance 
between  the  failure  of  a  tie  from  decay  and  from  wear  is  a  very 
difficult  one  to  obtain  with  our  present  limited  fund  of  data 
and  this  complicates  greatly  the  selection  of  a  proper  treating 
process.  Certain  general  rules  can,  however,  be  laid  down  which 
should  aid  in  selecting  the  proper  process  for  any  given  condi- 
tions. The  most  important  points  to  consider  in  this  connection 
are:  (1)  kind  and  form  of  ties  to  be  used,  (2)  the  tonnage  over  the 
road,  (3)  climatic  conditions,  and  (4)  type  of  track  construction. 
These  are  so  closely  interwoven  that  they  must  all  be  considered 
together. 

If  the  road  is  so  fortunate  as  to  run  through  or  tap  a  forested 
region  containing  strong,  durable  tie  material,  the  need  of  a 
preservative  treatment  is  not  pressing  and  may  even  be  dispensed 
with  entirely.  Thus,  if  ties  of  heart  cypress,  redwood,  and  cedar 


PROLONGING  THE  LIFE  OF  CROSS-TIES  149 

can  be  obtained  at  a  reasonable  price,  no  treatment  other  than 
a  protection  from  wear  is  required.  However,  this  condition 
rarely  exists,  so  that  some  method  of  increasing  the  resistance 
of  the  wood  to  decay  becomes  necessary.  If  the  wood  is  refrac- 
tory— that  is,  if  a  preservative  cannot  be  forced  into  it  except 
superficially — as  with  Douglas  fir,  tamarack,  etc.,  as  heavy  a 
treatment  as  possible  with  straight  creosote  will  probably  give 
most  efficient  results  because  even  at  best  only  small  amounts 
of  the  oil  will  be  absorbed.  If,  however,  the  wood  is  porous  and 
readily  absorbs  preservative,  then  some  cheaper  process,  like  the 
Burnett,  Card,  or  empty-cell  creosote  is  preferable.  The  same 
is  true  for  those  ties  which  are  cut  so  as  to  have  fairly  wide  strips 
of  sapwood  on  one  or  both  sides  while  the  faces  are  of  resistant 
heartwood  possessing  in  itself  little  durability. 

Obviously,  ties  which  have  a  heavy  tonnage  passing  over  them 
are  more  subject  to  failure  from  wear  than  ties  laid  in  a  track 
where  the  tonnage  is  light.  In  general,  such  ties  should  be  given 
a  less  efficient  and  expensive  treatment,  for  if  heavy  injections 
are  made,  considerable  quantities  of  preservative  will  be  destroyed 
with  the  ties. 

Climatic  conditions  must  be  carefully  considered.  Ties  laid 
in  regions  of  heavy  rainfall  had  best  be  treated  with  straight 
creosote.  In  arid  regions  and  where  rainfall  is  comparatively 
light,  zinc-treated  ties  may  be  advantageously  used. 

The  type  of  track  construction  has  much  to  do  with  the  selec- 
tion of  the  process.  In  general,  best  construction  enables  the 
use  of  the  more  effective  and  expensive  treating  processes.  For 
example,  a  track  laid  with  heavy  rail,  heavy  tie  plates,  screw 
spikes  and  a  firm  rock  ballast  would  call  for  a  more  costly  and 
effective  treating  process  than  one  laid  with  cut  spikes,  dirt 
ballast,  and  no  tie  plates.  It  should  not  follow  that  this  is  uni- 
versally true.  Suppose,  for  instance,  that  the  track  construction 
is  of  the  best,  but  that  the  ties  are  of  a  comparatively  soft  wood 
like  loblolly  pine;  it  is  the  author's  opinion  that  an  empty-cell 
process  should  be  selected  in  preference  to  a  full-cell,  as  it  would 
give  an  equal  length  of  life  to  the  tie  with  a  much  less  consump- 
tion of  preservative,  and  hence  the  expense  would  be  less.  As 
mentioned  above,  a  decision  on  the  selection  of  a  proper  timber- 
treating  process  for  ties  can  be  correctly  made  only  after  all  fac- 
tors affecting  the  life  of  the  tie  have  been  considered.  It  appears, 
therefore,  that  railroads  controlling  a  large  mileage,  especially, 


150        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

if  it  traverses  a  wide  territory,  should  use  more  than  one  process 
in  order  to  secure  most  economic  returns.  In  the  above  discus- 
sion, the  question  of  initial  cost  has  not  been  mentioned,  as  its 
effect  in  the  selection  of  a  process  is  so  obvious  as  to  need  no  special 
comment.  The  ideal  process  selected  may  be  the  cheapest 
process — Burnettizing,  for  example — in.  so  far  as  initial  cost  is 
concerned.  Or  the  ideal  process  may  be  the  most  expensive — 
full-cell  creosote — in  which  case,  if  the  company  could  not  afford 
it,  the  next  best  rather  than  none  at  all  should  be  selected.  A 
common  feature  is  that  practically  all  standard  processes  using 
pressure  pay  if  compared  to  the  use  of  untreated  ties,  so  the 
problem  reduces  itself  largely  to  a  question  of  which  pays  best. 

Cost  of  Treating  Ties. — The  total  cost  of  treating  ties  can  be 
divided  into  the  following  general  items :  (1)  seasoning,  (2)  labor, 
(3)  fuel,  (4)  plant  operation  and  maintenance,  and  (5)  chemicals. 

The  majority  of  ties  now  treated  in  the  United  States  are  air- 
seasoned  prior  to  treatment.  The  cost  of  this  varies  with  the 
kind  of  wood,  season  of  the  year,  and  geographical  location. 
In  general,  however,  seasoning  charges  range  from  about  0.50  to 
1.5  cents  per  tie. 

Labor  includes  all  forms  necessary  to  the  treatment,  such  as 
loading  and  unloading  of  ties  in  the  yard,  and  for  the  tie  plant 
and  superintendence.  It  also  varies  considerably,  but  ranges 
from  about  3  to  6  cents  per  tie. 

Fuel  is  least  in  those  plants  which  can  use  natural  gas  or  oil  and 
highest  in  those  most  remote  from  a  source  of  supply,  but  ranges 
from  about  1/2  to  2  cents  per  tie. 

On  account  of  the  corrosive  action  of  zinc  chloride,  the  life 
of  a  plant  using  that  kind  of  a  preservative  is  usually  reckoned  as 
shorter  than  that  of  one  using  creosote;  consequently,  its  de- 
preciation is  greater.  If  the  capacity  of  the  plant  is  lowered 
through  accident,  shortage  of  ties,  etc.,  the  depreciation  charges 
per  tie  will  be  very  high.  The  total  cost  of  maintenance,  includ- 
ing this  depreciation,  interest  on  the  investment,  etc.,  will  usu- 
ally range  from  1  to  2  cents  per  tie. 

Practically  all  of  the  ties  now  treated  in  commercial  plants  in 
the  United  States  are  injected  with  zinc  chloride  or  with  creosote, 
either  alone  or  in  combination.  Only  a  few  plants  use  preserva- 
tives like  crude  oil  and  mercuric  chloride.  It  is  customary  to 
inject  about  1/2  pound  of  dry  zinc  chloride  per  cubic  foot 
of  wood  although  this  varies  at  times  from  one-third  to  two- 


PROLONGING  THE  LIFE  OF  CROSS-TIES  151 

thirds  of  a  pound.  This  salt  costs  from  3  1/2  to  5  cents  per 
pound.  Creosote  costs  front,  about  7  to  12  cents  per  gallon  in 
large  quantities.  It  is  customary  in  tie  work  to  inject  from  5  to 
10  pounds  of  this  oil^per  cubic  foot. 

With  the  above  data  the  cost  of  tie  treatments  may  be  esti- 
mated. It  should  be  borne  in  mind,  however,  that  the  figures 
given  are  general,  and  will  not  apply  to  all  conditions.  Using 
them  as  a  basis,  however,  the  cost  of  treating  a  standard  7  inch 
X  9  inch  X  8  foot  tie  will  be  approximately  as  shown  in 
Table  13,  royalties  not  included.  It  is  understood  that  royalties 
are  now  charged  in  the  Rueping  and  Card  processes,  while  the 
Lowry  process  is  operated  under  certain  restrictions  by  the  com- 
pany which  controls  the  Lowry  patents.  For  the  other  proc- 
esses listed  in  the  table  no  royalties  are  required. 

TABLE  13. — APPROXIMATE  COST  OP  TREATING  TIES 

(Tie  7  inches  X  9  inches  X  8  feet) 


Process 

Cost  per  tie,  cents 

Burnett  
Wellhouse 

10-14 
12-16 

Card  

16-20 

Rueping  (a)  .  .  . 

25-29 

Lowry(6)  
Full-cell  cresote(c)  

32-35 
39-45 

a  =  assuming  about    6  pounds  of  creosote  per  cubic  foot  absorption. 
b  =  assuming  about    8  pounds  of  creosote  per  cubic  foot  absorption. 
c  =  assuming  about  10  pounds  of  creosote  per  cubic  foot  absorption. 
Assuming  creosote  costs  about  1  cent  per  pound  and  zinc  chloride  about 
4  cents  per  pound. 

It  will  be  noted  in  this  table  that  the  cost  of  the  preservative 
used  is  a  large  percentage  of  the  total  cost  of  treatment.  Creo- 
sote, for  example,  greatly  increases  the  cost  of  the  treatment  and 
when  it  is  used  in  comparatively  large  quantities — 8  pounds  or 
over  per  cubic  foot — all  other  costs  make  but  a  small  fraction  in 
the  total  cost  of  treatment.  The  opportunity  either  for  an  effi- 
cient preservative  at  lower  cost  or  for  some  modified  method  of 
operation  which  will  enable  a  high-priced  preservative  to  be 
better  utilized  than  is  being  done  in  present  practice  is  strik- 
ingly apparent. 

Economy  in  Treating  Ties. — There  is  no  longer  any  just  doubt 
but  what  the  preservative  treatment  of  ties  pays.  Unfortunately, 


152        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

reliable  records  on  the  life  of  treated  ties  which  have  been  in  ser- 
vice for  long  periods  are  too  meager  to  enable  exact  estimates  of 
actual  economy  to  be  made,  so  that  the  financial  saving  is  still  a 
matter  of  conjecture.  Because  of  this  condition  it  is  not  pos- 
sible to  state  what  process  of  treatment  is  most  economical, 
and  it  will  take  several  years  before  any  true  basis  for  such  state- 
ments will  be  warranted.  As  has  already  been  pointed  out, 
it  is  quite  likely  that  the  different  methods  of  treatment  now 
practised  will  be  found  to  have  rather  sharp  limitations  so  that 
they  will  not  overlap  and  compete  to  such  a  large  degree  as  at 
present.  The  different  kinds  of  ties,  the  different  types  of  con- 
struction, and  the  different  geographical  regions  traversed  by 
our  roads  will  demand  different  treatments. 

In  the  meantime,  the  best  that  can  be  done  is  to  use  what 
data  is  already  available  on  treated  and  untreated  ties  in  service, 
and  add  to  this  our  knowledge  on  the  efficiency  of  the  various 
preservatives  used,  the  action  of  wood-destroying  fungi,  and  the 
durability  and  susceptibility  to  treatment  of  the  various  woods 
now  used  for  manufacture  into  ties. 

While  the  saving  in  money  is  undoubtedly  the  most  important 
feature  which  the  railroads  will  consider,  nevertheless  it  is  be- 
lieved that  other  factors  should  not  be  overlooked.  If  a  process 
showing  lowest  annual  charges  is  selected,  it  may  be  it  does  not 
prolong  the  life  of  the  ties  as  much  as  some  other  process  having 
higher  annual  charges.  This  means  that  tie  removals  will  be 
more  frequent  and  the  roadbed  will  consequently  be  more  con- 
tinuously disturbed.  The  disadvantages  are  obvious.  Further- 
more, if  the  price  of  untreated  ties  shows  a  steady  advance,  the 
advantage  of  securing  as  long  a  life  as  possible  from  them  is 
readily  apparent. 

Because  of  the  many  factors  which  influence  the  economy 
resulting  from  treating  ties  and  because  of  the  uncertainty  of 
present  data  on  the  durability  of  ties,  estimates  on  saving  are 
here  given  for  only  two  processes — the  Burnett  and  full-cell 
creosote — as  these  represent  the  probable  extremes,  certainly  in 
so  far  as  initial  cost  is  concerned.  In  order  to  make  the  results 
comparable,  it  is  assumed  that  all  ties  are  plated,  the  plates  cost- 
ing 25  cents  per  tie,  and  that  the  cost  of  placing  the  ties  in  the 
track  is  15  cents.  Furthermore,  all  ties  are  subjected  to  the  same 
traffic  conditions  and  preliminary  treatment.  As  annual  charges 
best  show  resulting  economy  they  are  used  in  the  following  table 


PROLONGING  THE  LIFE  OF  CROSS-TIES 


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154        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

and  are  figured  on  the  cost  of  the  ties  in  the  track,  the  computation 
being  made  by  the  following  formula: 

I.OP-.Q.QP 
I.OP-  -  i 

Where    r    —  equivalent  annual  charge. 
R  =  initial  expenditure. 
p  =  rate  of  interest  (taken  as  5  percent). 
n  =  term  of  years. 

It  will  be  noted  that,  in  general,  the  ties  treated  with  creosote 
show  a  slightly  greater  economy  than  when  treated  with  zinc 
chloride.  In  this  connection,  however,  the  remarks  already 
made  concerning  the  selection  of  the  treating  process  should  be 
kept  in  mind;  that  is,  ties  treated  with  zinc  chloride  should  not 
be  laid  in  wet  localities.  If  ties  treated  by  this  method  are  laid 
in  such  regions  the  differences  shown  in  the  table  would,  of  course, 
be  considerably  greater. 

It  should  be  noted  that  greatest  economy  in  treating  ties  comes 
from  those  which  possess  little  durability  in  an  untreated  condi- 
tion, this  amounting  in  certain  cases  to  an  annual  saving  of  over 
20  cents  per  tie  per  year.  Least  saving  comes  from  ties  which 
are  resistant  to  treatment  and  which  do  not  possess  a  marked 
natural  durability.  Such  ties  ought  not  to  command  high  prices. 
In  fact,  it  is  exceedingly  likely  that  the  prices  now  paid  for  ties 
will  be  readjusted  as  reliable  data  on  their  serviceability  is  grad- 
ually obtained,  and  more  value  is  placed  upon  their  intrinsic 
properties.  Red  oak,  beech,  and  elm,  for  example,  will  become 
more  and  more  prized  as  good  tie  woods,  because  of  their  rapid 
growth,  hardness,  and  permeability. 

If  the  figures  given  in  the  table  are  found  by  actual  experience 
to  be  accurate,  the  difference  in  the  annual  saving  between  the 
two  processes  compared  is  insignificant.  This  does  not  mean, 
however,  that  the  selection  of  the  process  is  unimportant,  because 
other  factors  such  as  initial  cost,  ultimate  length  of  service,  local 
climatic  conditions,  etc.,  as  pointed  out  above,  must  also  be  taken 
into  consideration. 

Need  for  Test  Tracks. — It  is  apparent  from  the  above  discus- 
sion on  the  economy  of  treatment  that  little  of  definite  value  on 
the  efficiency  of  various  processes  can  be  determined  until  ac- 
curate data  is  available.  Without  doubt,  the  best  way  of  secur- 
ing such  data  is  to  set  aside  certain  portions  of  the  main  track, 


PROLONGING  THE  LIFE  OF  CROSS-TIES  155 

typifying  conditions  of  the  road,  for  experimental  or  test  purposes. 
Such  portions  of  the  track-  are  called  "test  or  experimental 
tracks.''  In  them  complete  records  should  be  kept  on  each  tie, 
such  as  kind  of  wood-,  how  treated,  when  and  how  laid,  and  notes 
on  its  character  of  failure  obtained  from  yearly  inspections.  In 
addition,  general  data  on  the  character  of  the  ballast,  type  of 
construction,  tonnage  over  the  road,  etc.,  should  be  made  a  matter 
of  record.  To  assist  in  identifying  the  ties,  each  tie  should  have 
zinc-coated  dating  nails  driven  into  it  at  some  readily  accessible 
point.  A  good  place  for  the  nails  is  about  1  foot  inside  the  rail. 

The  old  method  of  driving  dating  nails  into  all  treated  ties  and 
attempting  to  keep  records  on  all  of  them  has  not  proved  success- 
ful and  is  not  recommended.  Trackmen  as  a  rule  will  not  keep 
accurate  records  and  unless  the  records  are  accurate  they  are 
worse  than  useless,  as  they  may  lead  to  absurd  conclusions. 
The  direct  and  positive  value  of  the  data  secured  from  test  tracks 
enables  accurate  deductions  to  be  made  of  the  efficiency  of  the 
treatment  and  far  more  than  justifies  the  cost  of  placing  and 
maintaining  them. 


CHAPTER  IX 

PROLONGING  THE  LIFE  OF  POLES  AND  CROSS  ARMS 
FROM  DECAY  AND  INSECTS 

POLES 

Selection  of  Species. — According  to  present  usage,  in  order  to 
make  a  satisfactory  pole,  a  tree  must  have  the  following  general 
properties:  Its  wood  must  be  strong,  comparatively  light  in 
weight  and  durable,  its  taper  must  be  gradual  and  well  defined, 
its  form  must  be  straight,  and  in  addition  its  supply  must  be 
accessible  and  abundant.  These  requirements  necessarily  re- 
strict the  number  of  species  which  can  be  used.  For  example, 
of  the  3,000,000  poles  consumed  annually  in  the  United  States, 
over  two-thirds  are  cedar  and  about  one-seventh  chestnut. 
Hence,  over  80  percent  are  cut  from  only  two  kinds  of  wood. 

If  the  preservative  treatment  of  poles  was  more  generally 
practised,  a  much  larger  variety  of  woods  could  be  drawn  upon, 
since  they  possess  all  of  the  requisite  properties  save  durability. 
It  seems  apparent,  therefore,  that  as  the  present  supply  of  "pole 
woods"  becomes  more  and  more  exhausted  the  need  for  preserva- 
tive treatment  will  increase.  Such  woods  as  the  pines,  spruces, 
and  firs  should  prove  admirably  adapted  for  poles,  and  they  will 
undoubtedly  be  called  into  use.  In  fact,  a  movement  in  this 
direction  has  already  taken  place,  and  poles  cut  from  these  timbers 
are  now  being  used  in  several  places  in  the  West. 

Insects,  in  addition  to  decay,  also  attack  poles,  thus  weakening 
them  not  only  by  their  burrows  but  also  by  admitting  channels 
through  which  the  decay  can  enter  and  spread.  As  the  methods 
which  prevent  decay  will  also  prevent  insect  attack,  the  two  are 
discussed  in  common  in  this  chapter. 

Manufacture  of  Poles. — Most  of  the  poles  used  in  the  United 
States  are  simply  tree  trunks  which  have  been  trimmed  of  limbs 
and  then  peeled.  Very  few  sawed  poles  are  used.  As  has  already 
been  pointed  out  (Chapter  IV)  the  best  time  to  cut  timber  is  in 
winter  or  late  fall.  Poles  cut  during  this  period  are,  however, 
more  difficult  to  peel,  as  the  bark  clings  tenaciously  to  them, 

156 


PROLONGING  THE  LIFE  OF  POLES  157 

whereas  in  spring  long  strips  of  bark  can  readily  be  torn  from  the 
trunk.  It  is  very  important  to  peel  all  bark  from  that  portion 
of  the  pole  to  be  treated;  qt&erwise  the  bark  will  prevent  a  uni- 
form penetration  of  the  preservative. 

The  practice  of  dragging  poles  over  the  ground  for  long  dis- 
tances, thereby  grinding  off  the  outer  layers  of  wood,  should  be 
prohibited,  as  it  not  only  weakens  the  pole  but  makes  it  more 
susceptible  to  decay. 

It  is  also  bad  practice  to  saw  that  portion  of  the  pole  which 
projects  above  ground,  leaving  the  butt  the  natural  shape  and 
size  of  the  tree,  unless  the  butt  is  given  a  thorough  preservative 
treatment,  because  the  sap  on  the  butt  will  quickly  decay  and 
infect  the  heartwood.  If  sawing  must  be  done  on  account  of 
local  or  other  requirements,  it  is  better  to  saw  the  entire  pole.  As 
a  general  proposition,  however,  sawing  should  be  avoided  if  pos- 
sible. The  top  of  the  pole  should  also  be  cut  slanting  unless 
there  is  some  reason  why  this  cannot  be  done.  If  a  plate  or  cap 
is  placed  on  the  top  of  the  pole,  the  wood  underneath  should  be 
at  least  brush  treated  with  creosote.  Whenever  possible  the 
pole  should  be  trimmed  and  bored  to  exact  dimensions  before 
it  is  treated,  in  order  to  avoid  cutting  into  the  treated  wood  and 
thus  exposing  the  untreated  interior. 

Method  of  Seasoning. — Common  practice  now  pays  little  at- 
tention to  seasoning  poles.  (See  Plate  XV,  Fig.  A.)  Poles  are  gen- 
erally piled  one  on  top  of  the  other  in  order  to  occupy  as  little 
space  as  possible.  If  the  poles  are  not  to  be  treated  and  if  they 
are  not  held  too  long  in  these  piles  so  that  decay  will  attack  them, 
no  serious  objection  can  be  levied  against  this  practice.  Of 
course,  when  piled  in  this  manner,  the  rate  at  which  they  lose 
water  is  greatly  decreased  and  consequently  they  will  weigh 
more  when  shipped;  hence,  the  cost  of  transportation  is 
increased. 

If  the  poles  are  to  be  treated,  especially  by  the  open-tank  or 
brush  methods,  a  preliminary  air  seasoning  is  highly  desirable. 
The  best  way  to  do  this  is  to  roll  the  poles  on  skids  with  suf- 
ficient space  between  them  so  that  the  air  can  circulate  freely. 
These  skids  can  be  built  of  poles  placed  horizontally  and  ele- 
vated a  foot  or  more  above  the  ground.  If  space  permits,  but 
one  layer  of  poles  should  be  built  on  each  skid,  but  if  necessary, 
several  layers  can  be  piled  on  each  other.  (See Plate XV,  Fig.  B.) 

Factors  other  than  ease  of  handling  should  be  given  con- 


158        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


sideration  in  selecting  the  seasoning  yard.  For  example,  the 
ground  should  be  fairly  level,  well  drained,  and  as  free  from  weeds 
and  decayed  wood  as  possible.  The  poles  should  be  exposed  to 
the  sun  and  air  currents  so  that  the  seasoning  will  be  rapid. 
Too  rapid  seasoning,  however,  may  check  the  poles,  in  which 
case  they  can  be  piled  closer  together.  Incipient  checks,  which 
are  liable  to  increase  in  size,  should  be  protected  with  "S-irons" 
(Fig.  22). 

The  length  of  time  poles  should  be  seasoned  varies  primarily 
with  the  time  of  year,  the  kind  of  wood,  and  climatic  conditions. 


FIG.  22. — Method  of  applying  "S  "-irons  to  prevent  checking. 

From  a  large  number  of  tests  made  by  the  U.  S.  Forest  Service 
in  cooperation  with  the  American  Telephone  and  Telegraph 
Company  the  following  table  has  been  compiled : 

TABLE   15. — APPROXIMATE  TIME  REQUIRED  TO  AIR  SEASON  POLES  FOR 

TREATMENT 


No.  of  months  required  when  poles 

Species 

Region 

are  cut  in 

Spring 

Summer 

Autumn 

Winter 

Chestnut  

Maryland  

3 

3 

7 

6 

Southern  white  cedar.  .  .  . 

Carolinas  

2 

2 

4 

3 

Northern  white  cedar.  .  .  . 

Michigan  

5 

5 

9 

8 

Western  yellow  pine  

California  

5 

2 

9 

6 

The  above  figures  may  be  used  to  predict  the  seasoning  periods 
for  other  varieties  of  wood  not  listed,  although  just  how  accurate 
they  will  be  cannot  be  told  except  by  actual  trial. 

Because  of  its  comparatively  large  diameter,  the  moisture 
content  of  an  "  air-seasoned "  pole  varies  considerably.  For 
example,  the  outer  portion  may  contain  only  10  percent  of  moisture 


FIG.  A. — Cedar  poles  piled  for  storage,  Michigan.     (Forest  Service  photo.) 


FIG.  B. — Poles  properly  piled  for  air  seasoning,  Black  Forest,  Germany. 
(Forest  Service  photo.) 

(Facing  page  158.) 


PLATE  XV 


FIG.  C. — An  open  tank  pole  treating  plant.     A  popr  design,  note  creosote 
evaporating  from  tanks.     (Forest  Service  photo.) 


FIG.  D. — Creosoted  poles  for  heavy  construction,  Hayes,  England.     (Forest 

Service  photo.) 


PROLONGING  THE  LIFE  OF  POLES 


159 


while  the  interior  has  40  percent  or  over.  It  is  not  necessary 
or  practicable  to  reduce  this  interior  moisture  very  materially 
for  it  does  not  seriously  affject  any  preservative  treatment  which 
might  be  given. 

The  effect  of  this'moisture  loss  on  freight  shipments  is  very 
important,  especiallv  in  long  hauls. 

TABLE    16. — SHOWING  SAVING  IN  FREIGHT  EFFECTED  BY  AIR-SEASONING 

POLES 


Size  of  pole 

No.  of 
poles  re- 

Total de- 
crease in 

Saving    in    freight  on 
carload  lots 

Species 

Length, 

Top 

diam- 

quired for 
carload  of 

weight  due 
to  air 

25  cent 

15  cent 

feet 

eter, 
in. 

40,000 
Ib. 

seasoning 
(pounds) 

rate, 
dollars 

rate, 
dollars 

Chestnut 

30 

7 

43 

7,700 

19   25 

11  55 

Southern  white  cedar. 

30 

7 

74 

16,900 

42.25 

25.35 

Northern  white  cedar. 

30 

7 

91 

12,800 

32.00 

19.20 

Western  red  cedar  .... 

40 

8 

59 

12,900 

32.25 

19.35 

Western  yellow  pine.  .  . 

40 

8 

46 

38,400 

96.00 

57.60 

The  decrease  in  weight  from  a  green  to  an  air-dry  condition 
varies  from  about  20  to  50  percent,  or  180  to  850  pounds  per  pole. 
The  decrease  in  shipping  weight  and  freight  charges  is,  of  course, 
in  direct  proportion  to  these  percentages. 

The  shrinkage  in  the  circumference  of  poles  due  to  their  season- 
ing is  insignificant,  contrary  to  general  belief.  Consequently, 
if  a  pole  is  measured  when  green,  these  figures  can  be  considered 
as  practically  unaltered  by  subsequent  drying,  since  the  shrinkage 
will  not  exceed  1  percent.  Exact  data  on  shrinkage  taken 
from  measurements  on  about  2000  poles  of  chestnut,  cedar  and 
pine  averaged  from  0.3  to  0.5  percent  of  the  green  circumference 
6  feet  from  the  butt  to  0.6  to  0.9  percent  at  the  top.  This  is 
equivalent  on  30-  to  40-ft.  poles  to  about  0.1  or  0.2  inch  in 
the  circumference  of  the  butt  and  from  0.15  to  0.25  inch  at 
the  top. 

If  the  poles  are  steam  seasoned,  they  are  handled  in  much  the 
same  manner  as  cross-ties,  viz.,  placed  in  the  treating  cylinder 
and  subjected  to  live  steam  at  pressures  not  exceeding  40  pounds 
for  four  or  more  hours,  after  which  a  vacuum  is  applied  and  the 
preservative  injected. 

Methods  of  Treatment  and  Their  Selection. — Because  of 
their  large  size  and  the  high  cost  of  handling  and  shipping  them 
and  the  comparatively  small  number  assembled  at  one  point, 


160        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  treatment  of  poles  is  quite  a  different  problem  from  the  treat- 
ment of  ties.  Furthermore,  poles  are  not  subject  to  the  same 
kind  of  deterioration  as  ties.  That  portion  which  projects  above 
ground  is  much  less  subject  to  decay  than  that  in  the  ground, 
and  in  temperate  climates  like  the  northern  and  western  United 
States,  where  the  humidity  and  temperature  are  generally  low, 
the  tops  may  last  indefinitely.  In  warm,  humid  climates,  as  in 
the  South,  a  protection  to  the  top  is  desirable  and  often — as  in 
the  case  of  pines — necessary.  Poles  do  not  fail  from  mechanical 
wear,  so  that  this  factor  need  not  be  considered. 

Several  methods  of  protecting  the  life  of  poles  from  decay  and 
insects — the  chief  destructive  agents— are  practised.  These  are 
(1)  setting  the  poles  in  crushed  stone  or  concrete,  (2)  charring  the 
butts,  (3)  brush  treating  the  butts  with  a  wood  preservative, 
(4)  impregnating  the  butts  with  a  preservative,  and  (5)  impreg- 
nating the  entire  pole  with  a  preservative. 

Setting  in  Crushed  Stone  or  Concrete. — If  the  hole  into  which 
the  pole  is  to  be  placed  is  dug  several  inches  wider  than  the  pole, 
crushed  or  small  field  stones  can  be  pounded  around  the  pole 
after  it  is  set.  These  will  permit  more  or  less  circulation  of  air 
around  the  butt  and  keep  weeds  from  growing  close  to  the  pole. 
In  this  way  a  partial  protection  is  afforded  which  will  add  a  year 
or  two  to  the  life  secured.  Furthermore,  the  stones  will  tend  to 
protect  the  pole  from  ground  fires.  Sand  placed  in  such  holes 
affords  no  protection  and  may  even  hasten  decay.  The  author  has 
little  evidence  that  poles  set  in  concrete  are  materially  prolonged 
in  service.  Such  concrete  jackets  are  liable  to  become  broken 
and  hence  admit  water.  All  of  these  methods  are  considered 
make-shifts  and  should  be  used  only  when  no  better  treatment 
can  be  had. 

Charring. — Provided  the  poles  are  air  seasoned,  charring  to  a 
depth  of  1/4  in.  from  the  butt  to  about  2  ft.  above  ground  line 
will  more  than  pay  for  itself.  It  is,  however,  an  inefficient 
method  of  treatment  and  adds  but  little  to  the  life  of  the  pole. 
If  charred  green,  the  poles  are  very  liable  to  check  open  and  de- 
cay hastened  rather  than  retarded.  Charring,  furthermore, 
destroys  the  outer  fibers  of  the  wood  and  weakens  the  pole  where 
strength  is  most  needed.  Charred  poles  examined  by  the  author 
were  also  readily  attacked  by  insects. 

Brush  Treatment. — These  should  be  applied  to  poles  only 
after  they  are  air  seasoned.  If  applied  to  green  poles,  the  effec- 


PROLONGING  THE  LIFE  OF  POLES  161 

tiveness  of  the  treatment  will  be  greatly  decreased.  The  methods 
of  applying  brush  treatments  have  already  been  described  (see 
Chapter  V).  To  secure  best  results,  particularly  for  poles  set  in 
sandy  soil,  the  entire  butt  ^.d  end  of  the  pole  should  be  coated 
with  the  preservative  and  the  protection  should  extend  1  or 
2  feet  above  the  ground  line.  If  poles  are  well  treated  by  this 
method,  their  life  can  be  extended  from  3  to  6  years.  When 
no  better  method  can  be  afforded,  brush  treatments  are  recom- 
mended. The  best  preservative  thus  far  known  is  coal-tar 
creosote,  which  should  be  applied  hot  (about  160°  F.)  in  two 
coats.  For  reliable  results  secured  to  date  the  reader  is  re- 
ferred to  Fig.  118,  appendix. 

Open-tank  Butt  Treatments. — If  the  top  of  the  pole  is  not 
subject  to  decay,  a  butt  treatment  in  an  open  tank  is  the  best 
known-  (See  Plate  XV,  Fig.  C.)  (For  description  see  open-tank 
treatment,  Chapter  V.)  A  number  of  test  poles  treated  in 
this  manner  have  shown  excellent  results  (see  Fig.  31  and  Fig.  32, 
appendix),  and  because  the  preservative  is  confined  to  the 
butt  of  the  pole  where  decay  is  most  active,  the  method  is 
more  economical  than  if  the  entire  pole  is  impregnated.  Un- 
fortunately, in  order  to  cut  down  labor  and  maintenance  costs, 
such  treatments  are  feasibly  only  where  comparatively  large 
numbers  of  poles  are  assembled  at  one  point.  Furthermore,  the 
treatment  may  mean  a  delay  in  shipment,  although  it  is  felt 
that  this  objection  should  be  met  on  the  part  of  pole  consumers 
by  anticipating  their  orders  in  sufficient  time  to  enable  the 
treatment  to  be  made. 

Coal-tar  creosote  to  the  amount  of  10  pounds  per  cubic  foot, 
or  more  if  possible,  will  give  best  results.  It  is  possible,  how- 
ever, to  impregnate  the  butts  with  zinc  chloride  or  other 
antiseptic  salts,  either  alone  or  in  combination  with  the  creosote, 
in  which  case  a  decrease  in  the  cost  of  the  preservative  can  be 
made.  In  any  event,  the  aim  should  be  to  treat  all  of '  the 
sapwood  to  a  height  of  1  to  2  feet  above  ground  level. 

Butt  treatments  are  now  given  which  often  amount  to  little 
more  than  dipping  treatments,  and  while  they  are  better  than 
a  mere  brushing  of  the  pole,  they  will  not  prove  as  effective  as 
though  the  preservative  is  driven  through  the  sapwood.  In 
some  cases,  the  surface  of  the  pole  has  been  perforated  with  small 
holes  in  order  to  facilitate  the  entrance  of  the  preservative  and 
shorten  the  time  of  treatment. 
11 


162        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Poles  to  be  butt-treated  are  hoisted  by  a  derrick  into  open  tanks, 
where  they  are  stood  on  end.  The  preservative  is  then  admitted 
until  the  butts  are  submerged.  If  creosote  or  a  similar  oil  is  used, 
it  is  heated  to  about  215°  F.  for  two  or  more  hours,  after  which 
it  is  permitted  to  cool,  or  cool  oil  is  pumped  into  the  tank  and  the 
butts  kept  submerged  until  the  desired  absorption  is  obtained. 
In  a  similar  manner  the  poles  can  be  treated  with  zinc  chloride. 
By  running  the  hot  oil  out  of  the  tank  and  admitting  a  zinc- 
chloride  solution,  a  combination  treatment  can  be  obtained,  or 
the  poles  can  be  lifted  out  of  the  hot  tank  and  stood  in  a  second 
tank  containing  the  solution.  Table  17  gives  some  results 
secured  in  butt-treating  poles  by  the  open-tank  method  and  shows 
the  amount  and  depth  to  which  the  preservative  was  absorbed.1 

TABLE  17. — AVERAGE  ABSORPTION  AND  PENETRATION  OF  CREOSOTE   OB- 
TAINED IN  THE  BUTT  TREATMENT  OP  POLES  BY  THE 
OPEN-TANK  METHOD 


Species 

Absorp- 
tion  per 
pole 

Pene- 
tration 

Species 

Absorp- 
tion per 
pole 

Pene- 
tration 

Chestnut  

Pounds 
21  5 

Inches 
0  3 

i 

Western   yellow 

Pounds 

Inches 

Northern  white 

pine 

81  4 

3  1 

cedar  

48.4 

0.5 

Lodgepole  pine... 

34  0 

1  0 

Western  red  cedar 

39.5 

0.8 

Entire  Impregnation. — If  the  poles  decay  in  the  top  as  well  as 
in  the  butt,  the  entire  pole  should  be  treated.  This  is  done  by 
placing  them  on  cylinder  cars  and  running  them  into  a  treating 
cylinder.  The  treatment  is  very  similar  to  that  given  ties,  no 
special  apparatus  being  required  except  that  the  cars  should  be  of 
the  bolster  type  in  order  to  take  curves.  The  best  process  is  the 
full-cell  creosote  injecting  about  10  pounds)  of  oil  per  cubic  foot. 
This  method  of  treatment  is  most  expensive  on  account  of  the 
large  amount  of  creosote  absorbed.  It  should  not  be  used  if 
open-tank  treatments  will  suffice.  A  modified  treatment  has  been 
suggested  whereby  the  poles  are  run  into  horizontal  cylinders 
mounted  on  pivot  bearings,  after  which  the  cylinder  is  revolved 
to  a  vertical  position.  In  this  way  it  is  possible  to  impregnate 
the  butt  under  pressure  and  give  the  top  of  the  pole  a  lighter 
treatment,  thus  saving  materially  in  total  cost.  So  far  as  known 


1  Bulletin  84,  U.  S.  Forest  Service,  by  Wm.  H.  Kempfer. 


PROLONGING  THE  LIFE  OF  POLES  163 

to  the  author,  this  method  has  not  been  practised  thus  far, 
although  it  has  much  to  comniend  it. 

Boucherie  Process. — In  this  process,  which  is  extensively  used 
in  France  and  which  Jias  been^tested  in  our  country,  the  poles  are 
treated  green  and  before  the  bark  is  removed.  (See  Plate  XVI, 
Fig.  A.)  In  fact,  the  sooner  the  treatment  can  be  given  after  the 
trees  are  cut  the  better  the  results  secured.  A  clamp  is  placed  over 
the  butt  of  the  pole,  which  is  placed  in  a  horizontal  position; 
through  this  clamp  a  hole  is  bored,  into  which  a  wooden  plug 
is  inserted.  The  plug  is  connected  to  a  hose,  which  in  turn  is 
fastened  to  a  larger  hose  or  pipe.  A  barrel  or  other  vessel  filled 
with  copper  sulphate,  and  elevated  about  20  ft.  above  the  pole  so 
as  to  give  a  static  pressure,  is  connected  by  means  of  a  hose  to 
this  feed  pipe.  In  this  way  the  copper-sulphate  solution  runs 
out  of  the  overhead  tank  and  forces  its  way  into  the  butt  of 
the  pole  and  eventually  through  its  entire  length.  As  soon  as 
the  solution  appears  at  the  top  end,  the  pole  is  disconnected 
from  the  treating  apparatus,  after  which  it  is  peeled,  trimmed, 
and  air  seasoned.  It  is  then  ready  for  use. 

The  Boucherie  process  is  very  well  adapted  to  the  treatment 
of  poles  in  small  quantities  and  in  rough  country  where  there  is 
a  supply  of  timber  suitable  for  poles  and  where  the  cost  of  trans- 
porting treated  poles  would  be  prohibitive.  Experiments  with 
this  process  were  made  by  the  U.  S.  Forest  Service  in  California, 
the  time  required  to  impregnate  the  various  poles  being  given  in 
Table  18. l  The  poles  were  treated  green  under  a  pressure  of 
about  10  pounds.  Their  length  was  about  22  ft. 

TABLE  18. — TIME  REQUIRED  TO  TREAT  GREEN  POLES  BY  THE  BOUCHERIE 

PROCESS 


Species 

Average  time  required  to  impregnate  poles 

Yellow  pine  
White  fir 

(Days) 
3.5 
2.9 

Douglas  fir  
Incense  cedar                              

6.2 
1.9 

Sugar  pine  

3.1 

Kyan  Process. — This  process  has  been  used  extensively  in 
Europe  for  treating  poles  and  has  given  very  good  results.     The 

1  From  report  by  Geo.  M.  Hunt  and  C,  S.  Smith,  of  the  U.  S.  Forest 
Service. 


164        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

manner  in  which  the  process  is  operated  has  been  described  in 
Chapter  V.  Next  to  poles  impregnated  by  the  full-cell  process, 
Kyanized  poles  have  given  greatest  durability.  The  treatment 
is  comparatively  inexpensive  when  compared  with  the  full-cell 
creosote  and  in  addition  the  surface  of  the  poles  is  clean  and 
free  from  oily  exudations.  It  is  believed  the  process  can  be 
adapted  to  many  conditions  in  our  country  and  is  well  worthy 
of  a  more  extended  trial.  While  no  tests  which  have  been  made 
are  known  by  the  author,  it  is  probable  that  a  treatment  with 
mercuric  chloride  can  be  given  poles  in  much  the  same  manner 
as  they  are  now  treated  by  the  Boucherizing  process,  although 
the  uniformity  of  the  penetration  might  not  be  as  good  as  when 
the  poles  are  first  air  seasoned. 

Reenforcing  Decayed  Poles. — The  expense  of  replacing  de- 
cayed poles  with  new  ones  is  considerable,  as  all  the  wires  must 
be  restrung,  in  addition  to  replacing  the  pole  proper.  For  this 
reason,  some  companies  have  attempted  to  reenforce  their  de- 
cayed poles  in  an  effort  to  prolong  their  life.  Two  methods 
have  been  rather  extensively  tried,  viz.,  reenforced  stubs  and  re- 
enforced  jackets.  The  former  consists  in  placing  a  stub  buried 
in  the  ground  next  to  the  pole  and  bolting  or  wiring  the  pole  to 
it.  (See  Plate  XVI,  Fig.  B .)  These  stubs  are  often  creosoten  by 
the  brush  or  full-cell  method.  They  undoubtedly  increase  the 
strength  of  the  decayed  pole  but  their  reenforcement  is  only 
temporary  and  final  removal  is  generally  deferred  for  but  a  com- 
paratively short  period. 

An  effective  method  consists  in  cutting  all  decayed  wood 
from  the  pole  for  some  distance  below  and  above  ground.  The 
pole  is  then  brush  treated  with  a  preservative  like  creosote,  after 
which  steel  reenforcing  rods  are  driven  into  it  and  the  whole 
buried  in  creosote.  This  method  is  claimed  to  give  very  good 
results  and  add  materially  to  the  strength  and  life  of  the  pole. 
No  definite  records  on  the  added  life  thus  secured  are,  however, 
known  to  the  author,  but  an  estimated  life  of  8  to  10  years  is 
claimed.  The  cost  of  such  a  treatment  is  about  $3.50  to  $5  per 
pole.  (See  Plate  XVI,  Fig.  C.) 

In  some  cases,  after  a  pole  has  decayed,  it  is  cut  off  at  the 
ground  line,  the  decayed  butt  removed,  and  the  pole  lowered 
in  the  same  hole.  This  practice  is  common  and  feasible  when 
the  length  of  the  pole  is  sufficient  to  stand  this  shortening.  It 
is  believed  that  better  results  would  be  secured  if  the  sound  por- 


PLATE  XVI 


FIG.  A.— A  Boucherie  pole  treating  plant,  Fulda,  Germany.     (Forest  Serv- 
ice photo.) 


FIG.  B. 


(Forest 


-Partially  decayed  pole  reenforced  with  a  creosoted  stub. 
Service  photo.) 

(Facing  page  164  ) 


PLATE  XVI 


PROLONGING  THE  LIFE  OF  POLES 


165 


tion  of  the  pole  was  given  two  coats  of  hot  creosote  before  it  was 
lowered  into  the  ground.  As  ihe  ground  about  the  hole  is  in- 
fected with  decay-producing  fungi,  the  life  of  a  pole  set  in  such  soil 
will  not  be  as  great  as  the  life  of&  pole  set  in  a  freshly  dug  hole. 

Cost  of  Treatment. — The  cost  of  treating  poles  varies  through 
wide  limits.  It  depends  chiefly  upon  (1)  the  process  used,  (2) 
the  size  of  the  pole,  (3)  the  cost  of  the  preservative,  (4)  the  cost  of 
labor,  and  (5)  the  number  of  poles  treated  per  day.  In  order  to 
have  some  general  data,  however,  Table  19  has  been  compiled, 
but  in  using  it  the  reader  is  cautioned  against  drawing  too  sharp 
conclusions.  Creosote  is  assumed  to  cost  I  cent  per  pound, 
labor  $2  per  day,  the  size  of  pole  to  be  30  feet;  and  the  treatments 
given  as  already  described. 

TABLE  19. — ESTIMATED  COST  OF  TREATING  POLES 


Kind  of  treatment 

Amt.  of  preserva- 
tive used  per  pole 
(pounds) 

Cost  per  pole 

Field  or  crushed  stone  around  pole 

$0  00-SO  20 

Charring  butt  

0.05-  0.15 

Brush  treatment  (2  coats  creosote)  ..... 
Open-tank  butt  treatment  creosote 

8a 

506 

0.15-  0.30 
1  00-  1  50 

Entire  pole  treated  —  full-cell  creosote  

144C 

1.70-  2.25 

0  =  about  24  square  feet  surface. 
6  =  about    6  cubic  feet  treated. 
c  =  about  18  cubic  feet  treated. 

A  more  detailed  estimate  of  the  cost  of  butt-treating  poles, 
based  on  an  open-tank  plant  having  a  daily  capacity  of  120  poles 
per  day  or  30,000  per  year  (250  working  days),  is  as  follows:1 

LABOR  PER  DAY 

1  yard  foreman $4 . 00 

1  plant  engineer 4 . 00 

1  stationary  engineer 4 . 00 

2  firemen,  at  $2.50 5.00 

5  laborers,  at  $2 10.00 


Total $27.00 

Labor  charge  per  pole $0 . 225 

FUEL  PER  DAY 

2  tons  coal,  at  $4 $8 . 00 

Fuel  charge  per  pole 0 . 067 

bulletin  84,  U.  S.  Forest  Service. 


166        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

MAINTENANCE  PER  YEAR 

Depreciation  and  repairs $500 . 00 

Interest  on  investment  in  plant  and  preservatives   400 . 00 

Total $900.00 

Maintenance  charge  for  pole $0 . 030 

Seasoning  charge  per  pole  (interest  on  investment) 0 . 100 

Total  treating  charge,  exclusive  of  preservative $0.422 

The  cost  of  treatment,  exclusive  of  preservative,  based  on  a 
liberal  estimate  for  all  charges,  is  thus  seen  to  be  $0.422  per  pole. 
To  this  should  be  added  the  cost  of  the  preservative,  taxes  on 
property,  and,  if  the  treating  plant  is  not  located  at  a  central 
seasoning  or  distributing  yard,  extra  shipping  charges. 

Economy  of  Treatment. — Treated  poles  have  not  been  in  use 
in  this  country  for  a  sufficient  period  to  furnish  actual  data  on 
the  length  of  time  their  life  has  been  prolonged.  In  Germany, 
where  fairly  accurate  information  is  at  hand,  the  following  results 
have  been  secured  based  on  about  50  years  experience : 

Untreated  poles 7.7  years  average  life 

Poles  treated  with  copper  sulphate 11.7  years  average  life 

Poles  treated  with  zinc  chloride 11.9  years  average  life 

Poles  treated  with  mercuric  chloride 13.7  years  average  life 

Poles  treated  with  creosote 20 . 6  years  average  life 

The  amount  of  creosote  injected  in  each  case,  and  the  exact  con- 
ditions under  which  the  poles  were  set,  are  not  known.  We  have 
records  in  this  country,  however,  of  longleaf  pine  poles  treated 
by  the  full-cell  creosote  process  and  set  in  Virginia  which  are 
perfectly  sound  after  18  years'  service.  Accurate  records  on 
the  durability  of  poles  in  the  United  States,  so  far  as  these  are  at 
present  obtainable,  are  given  in  Fig.  31  and  Fig  32,  appendix. 
Using  them  and  the  cost  of  treatments  given  above,  the  econ- 
omy of  treatment  can  be  approximated  as  in  Table  20. 

It  will  be  noted  from  the  estimates  given  in  the  table  that  poles 
butt-treated  with  creosote  by  the  open-tank  method  are  the 
cheapest  to  maintain.  In  this  connection,  however,  several 
factors  should  be  kept  clearly  in  mind.  It  has  been  assumed  in 
the  table  that  the  tops  of  the  poles  do  not  decay.  While  this 
condition  is  true  for  a  large  part  of  our  country,  it  must  not  be 
universally  applied.  If  the  top  is  subject  to  decay,  the  full-cell 
creosote  process  will  undoubtedly  be  found  to  give  lowest  main- 


PROLONGING  THE  LIFE  OF  POLES 


167 


tenance  charges,  although  its  initial  cost  of  installation  will  re- 
main highest.  Another  very  important  point  is  the  kind  of  wood 
used  in  the  pole.  Northern  white  cedar  has  been  selected  in  the 
table  because  of  its  uniform  excellence  and  very  extended  use. 
If  other  varieties  are  employed  the  annual  charges  shown  in 
the  table  will,  of  course,  be  materially  changed.  For  example, 
a  loblolly  pine  pole  will  last  untreated  about  4  years,  whereas  the 
northern  white  cedar  is  estimated  at  14  years.  When  given  a 
butt  or  full-cell  treatment  with  creosote,  the  difference  in  the 
annual  charges  between  treated  and  untreated  loblolly  pine  poles 
will  be  much  greater  than  the  differences  between  treated  and 
untreated  cedar  poles,  because  of  the  natural  durability  of  the 
latter.  Consequently,  poles  possessing  less  natural  durability 
will,  when  treated,  show  greater  economy  in  treatment  than  poles 
possessing  great  natural  durability.  Furthermore,  the  lower 
price  at  which  such  poles  can  generally  be  secured  will  frequently 
make  their  use,  when  properly  treated,  cheaper  than  the  more 
naturally  durable  poles.  The  wide  range  through  which  these 
conditions  vary  frustrates  any  attempt  to  arrange  them  in  a 
table  that  would  be  of  practical  value,  hence  no  attempt  to  do  so 
has  been  made. 

TABLE  20. — ESTIMATED  ANNUAL  CHARGES  OF  CEDAR  POLES  TREATED  BY 
VARIOUS  METHODS 


]  Method  of  Treatment 

Cost  of 
treatment 

Cost  of 
pole  set  in 
line 

Estimated 
life 

Annual 
charge 

Untreated  

$ 

$ 

7  00 

Years 
14 

$ 

0  71 

Charred  at  butt 

0  15 

7  15 

15 

0  69 

Butt  brush-treated  

0.25 

7.25 

18 

0.62 

Boucherie     .          

0  70 

7  70 

20 

0  62 

Butt  treated  zinc  chloride   (open 
tank)  

0.60 

7.60 

22 

0.58 

Butt    treated    mercuric    chloride 
(open  tank)  

0.90 

7.90 

24 

0.59 

Butt  treated  creosote  (open  tank). 
Full-cell  creosote  (pressure;  

1.25 
2.29 

8.35'1 
9.501 

30 
30 

0.54 
0.62 

Pole —  northern  white  cedar. 
Life —  untreated  =  14  years. 
Cost  of  pole  =  $4. 


Cost  of  placement  =  $3. 
Size  of  pole  =  30  feet. 
Interest  5  percent  compounded  an- 
nually. 


1  Extra  charge  for  increased  weight  due  to  treatment. 


168        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

CROSS  ARMS 

Selection  of  Species. — Two  kinds  of  wood,  Douglas  fir  and 
pine  (mostly  longleaf),  furnish  about  90  percent  of  the  3,500,000 
cross  arms  used  annually  in  the  United  States.  Other  varieties 
such  as  oak,  cypress,  spruce,  junipe::,  cedar,  chestnut,  and  locust 
are  also  used,  but  in  scattering  quantities.  Due  to  the  manner 
in  which  they  are  placed,  decny  in  cross  arms  is  not  nearly  as 
serious  as  decay  in  poles.  The  problem  of  selecting  material 
for  cross  arms  is  therefore  largely  confined  to  those  species  which 
occur  in  sufficient  quantities  in  one  locality  and  thus  warrant  the 
installation  of  the  special  machinery  necessary  to  manufacture 
cross  arms  at  low  cost.  Douglas  fir  and  longleaf  pine  are  the 
woods  now  most  largely  manufactured  into  lumber  and  occur 
in  enormous  stands  over  a  wide  area.  The  intrinsic  properties 
desired  in  a  cross  arm  are  strength,  freedom  from  warping  and 
checking,  a  comparatively  light  weight,  and  resistance  to  decay. 
Even  when  the  arms  are  to  be  treated,  their  ability  to  absorb  the 
preservative  is  not  of  prime  importance,  as  only  small  quantities 
of  an  efficient  preservative  are  necessary  in  order  to  protect  them 
from  decay.  For  greatest  strength  at  least  weight,  redwood  is 
one  of  the  best  cross-arm  materials  used  and  it  is  surprising  that 
more  redwood  arms  are  not  in  service.  A  distinction  is  made 
between  arms  cut  from  Douglas  fir,  the  trade  recognizing  two 
distinct  types  known  as  " yellow"  and  "red"  fir.  The  former 
is  claimed  to  be  the  better  arm  and  far  more  durable  than  the 
latter,  cases  being  on  record  where  such  arms  untreated  were  in 
service  over  40  years  without  any  signs  of  decay.  It  is  probable, 
however,  that  this  long  service  was  due  to  the  comparatively 
dry  climate  (Utah)  in  which  these  arms  were  used. 

The  Manufacture  of  Cross  Arms. — It  is  quite  essential  that 
the  wood  from  which  cross  arms  are  made  be  of  straight  grain 
free  from  defects  such  as  knots,  spiral  grain,  checks,  etc.,  which 
tend  to  decrease  their  strength.  This  is  especially  true  for  that 
portion  of  the  arm  at  and  near  the  middle,  as  failure  is  most 
likely  to  occur  at  this  portion. 

It  is  also  important  to  have  the  arm  brought  to  exact  dimen- 
sions and  all  holes  bored  before  any  preservative  treatment  is 
given. 

Methods  of  Seasoning. — On  account  of  their  comparatively 
small  size  and  the  ease  with  which  they  can  be  handled,  cross 


PROLONGING  THE  LIFE  OF  POLES 


169 


arms  are  generally  air  seasoned  before  they  are  shipped  or  treated. 
The  usual  precautions  for  the  condition  of  the  seasoning  yard,  as 
described  in  Chapter  VHP;  hold  as  well  for  cross  arms.  Many 
forms  of  piles  have  been  tried%ut  those  which  give  best  satisfaction 
are  open  piles  without  roofs,  in  which  the  end  arms  in  each  tier 
are  placed  with  their  depth  vertical  while  the  arms  in  between 
are  placed  with  their  depth  horizontal.  (See  Plate  XVII,  Fig.  A.) 
This  allows  a  free  circulation  of  air  and  induces  rapid  drying. 

From  a  large  number  of  measurements,  the  shrinkage  in  con- 
iferous cross  arms  from  a  green  to  air-dry  condition  is  of  little  or 
no  practical  significance.  The  same  holds  for  any  changes  in  the 
shape  of  the  holes  bored  into  the  arms.  In  hardwood  cross  arms 
these  changes  are  much  greater. 

Cross  arms  season  rapidly  and  reach  an  air-dry  condition  in 
about  1  month.  In  summer  this  rate  may  even  be  exceeded, 
while  in  winter  or  rainy  weather  longer  periods  are  of  course 
necessary.  Some  experiments  were  made  by  the  U.  S.  Forest 
Service  in  air-seasoning  loblolly  pine  arms,  which,  according  to 
the  amount  of  sapwood  they  contained,  were  divided  in  three 
charges,  heartwood,  sapwood,  and  intermediate.  The  manner 
in  which  these  arms  seasoned  is  shown  in  Table  2 1.1 

TABLE  21. — COMPARATIVE   RATES  OF  SEASONING  OF  LOBLOLLY   PINE 
HEARTWOOD,  SAPWOOD,  AND  INTERMEDIATE  CROSS  ARMS 


Days 
seasoned 

Heartwood 

Sapwood 

Intermediate 

Weight 
per  arm 

Weight 
per  cu- 
bic foot 

Mois- 
ture 
content 

Weight 
per 
arm 

Weight 
per    cu- 
bic foot 

Mois- 
ture 
content 

Weight 
per 
arm 

Weight 
per    cu- 
bic foot 

Mois- 
ture 
content 

0  

Pounds 
38.8 
34.2 
33.9 
34.3 
34.2 
33.9 
33.6 

Pounds 
42.6 
37.6 
37.3 
37.3 
37.6 
37.3 
36.9 

Percent 
51.5 
33.4 
32.5 
33.8 
33.7 
32.3 
31.2 

Pounds 
52.7 
34.5 
32.6 
32.6 
32.5 
32.1 
31.6 

Pounds 
57.9 
37.9 
35.8 
35.8 
35.7 
35.3 
34.7 

Percent 
105.8 
23.8 
27.2 
27.3 
26.9 
24.5 
23.6 

Pounds 
45.8 
34.8 
33.3 
33.4 
33.4 
33.0 
32.5 

Pounds 
50.3 
37.7 
36.6 
36.7 
36.7 
36.3 
35.7 

Percent 
79.0 
34.0 
30.0 
30.3 
30.3 
29.0 
26.9 

30  

60  

90  

120  
150  
ISO  

Methods  of  Treatment  and  Their  Selection. — As  above  stated, 
cross  arms  are  not  subject  to  severe  attack  by  fungi,  since  they  are 
surrounded  on  all  sides  by  air  and  are  raised  a  considerable  dis- 
tance above  ground.  Decay  is  most  likely  to  occur  at  the  bolt 
and  pin  holes.  It  is  quite  essential,  therefore,  to  have  these  prop- 
erly protected.  If  the  arm  is  of  a  naturally  durable  wood  such  as 
white  or  red  cedar,  heart  cypress,  etc.,  no  preservative  treatment 

1  Circular  151,  U.  S.  Forest  Service. 


170        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

is  necessary,  as  the  arm  will  unquestionably  last  much  longer  than 
the  pole.  If,  however,  the  wood  is  not  so  durable,  such  as  pine, 
fir,  spruce,  etc.,  a  preservative  treatment  is  desirable. 

If  the  preservative  selected  is  a  salt,  such  as  zinc  or  mercuric 
chloride,  objections  can  be  raised  in  that  it  will  tend  to  wash  from 
the  wood,  it  will  attack  the  iron  spikes  or  bolts,  and  it  will  tend 
to  keep  the  arms  more  or  less  moist  thus  lowering  the  strength 
of  the  arms  and  decreasing  their  resistance  to  the  leakage  of 
electric  current. 

On  the  other  hand,  if  creosote  is  used,  it  will  tend  to  volatilize 
quickly  from  the  arms,  or  if  large  quantities  are  injected  danger 
from  drip  may  be  encountered.  Cases  are  on  record  where  com- 
panies have  been  forced  to  replace  their  arms  because  of  the  dam- 
age done  by  such  dripping.  Arms  heavily  creosoted  are,  more- 
over, increased  perceptibly  in  weight. 

Taking  all  these  factors  into  consideration,  it  is  believed  that 
arms  treated  with  about  5  to  6  pounds  of  creosote  per  cubic  foot 
by  an  empty-cell  process  so  that  no  drip  will  occur  will  give 
best  results.  In  doing  this,  however,  it  is  important  to  use  a 
high-grade  preservative,  so  that  loss  from  volatilization  can  be 
kept  to  a  minimum. 

Dipping  the  arms  in  a  tank  of  hot  preservative  such  as  coal- 
tar  creosote  or  carbolineum  for  several  minutes  should  also  give 
good  results.  The  oil  will  run  into  all  checks  and  holes  and,  as 
wood  is  most  easily  treated  in  the  direction  of  the  grain  (longi- 
tudinally), a  good  penetration  will  be  secured  at  those  points 
which  require  greatest  protection. 

Kyanized  arms  are  reported  to  have  given  excellent  service. 
The  process  produces  clean  arms  and  adds  practically  no  dead 
weight. 

Cost  of  Treatment. — The  cost  of  treating  cross  arms  is  very 
variable.  When  large  quantities  are  handled  and  apparatus  is 
at  hand  for  doing  the  work  mechanically,  the  cost  is  kept  at  a 
minimum.  It  has  been  assumed  in  the  estimates  given  in  Table 
22  that  these  mechanical  features  have  been  provided. 

TABLE  22. — APPROXIMATE  COST  OF  TREATING  CROSS  ARMS 


Process  used 

Total  cost  per  arm  (10-pin)   (cents) 

Full-cell  creosote  

10-20 

Empty-cell  creosote 

7-10 

Dipping  creosote  
Dipping  carbolineum  

4-  8 
10-30 

PLATE  XVII 


FIG.  A. — Cross  arms  properly  piled  for  air  seasoning.     (Forest  Service 

photo.) 


FIG.  B. — Creosoted  cross  arms  just  leaving  the  treating  cylinder,  Norfolk 
Creosoting  Co.     (Forest  Service  photo.) 

(Facing  page  170.) 


PLATE  XVII 


FIG.  C. — Fence  posts  properly  piled  for  air  seasoning.     (Forest  Service 

photo.) 


FIG.  D. — Untreated  lodgepole  pine  post  set  four  years.     Note  decay  at  the 
ground.     (Forest  Service  photo.) 


PROLONGING  THE  LIFE  OF  POLES 


171 


Economy  of  Treatment. — Only  estimates  based  upon  the  opin- 
ions of  operators  and  our  knowledge  of  the  decay  of  wood  can  be 
given  in  arriving  at  the  probable  economy  resulting  from  the  pre- 
servative treatmenjt  of  arms.  No  authenticated  records  are 
known  to  the  author  of  the  service  secured  from  treated  arms  in 
actual  use.  It  is  only  reasonable  to  expect  that  climatic  condi- 
tions will  affect  very  materially  the  life  of  cross  arms.  For  ex- 
ample, arms  in  the  South  where  the  air  is  often  warm  and  moist 
will  tend  to  decay  much  more  rapidly  than  arms  in  dry  or  cold 
climates.  In  fact,  it  is  doubtful  whether  the  treatment  of  arms, 
other  than  a  mere  soaking  in  the  preservative  of  the  bolt  and  pin 
holes  and  the  center  portion  in  contact  with  the  pole,  under  these 
latter  conditions  is  at  all  feasible  or  necessary.  As  has  been 
stated,  cases  are  on  record  of  yellow  fir  arms  which  in  a  com- 
paratively dry  climate  like  Utah  and  Nevada  lasted  untreated 
for  over  40  years  without  any  signs  of  decay.  Of  course,  such 
conditions  cannot  be  expected  for  the  greater  part  of  our  country, 
so  that  a  treatment  of  some  sort  is  generally  advisable. 

The  estimates  given  in  Table  23  are  very  rough  as  no  data 
could  be  found  giving  the  lives  of  cross  arms  treated  in  the 
manner  suggested. 

TABLE  23. — ESTIMATED  ANNUAL  SAVING  DUE  TO  TREATMENT  OF  CROSS 
ARMS  (INTEREST  COMPOUNDED  AT  5  PERCENT) 


Item 


Fir 


Pine 


Life  untreated  (years) 

Life  treated  by  empty-cell  process  (years) 

Life  treated  by  dipping  process  in  creosote  (years) .... 
Life  treated  by  dipping  process  in  carbolineum  (years) 

Cost  untreated  in  place  (dollars) 

Cost  treated  by  empty-cell  process  in  (place) 

Cost  treated  by  dipping  process  using  creosote 

Cost  treated  by  dipping  process  using  carbolineum . .  . 

Annual  charges  untreated 

Annual  charges  treated  by  empty-cell  process 

Annual  charges  treated  by  dipping  process  (creosote) . 
Annual  charges  treated  by  dipping  process  (carbolineum) 


15.0 

25.0 

20.0 

21.0 
1.50 
1.58 
1.56 
1.60 
0.150 
0.110 
0.125 
0.125 


10.0 
30.0 
18.0 
19.0 


50 
58 
56 
,60 
0.190 
0.100 
0.130 
0.130 


CHAPTER  X 

PROLONGING  THE  LIFE  OF  FENCE  POSTS  FROM 
DECAY 

Selection  of  Species. — Where  trees  abound,  fence  posts  are 
generally  made  from  timber  easiest  to  cut.  For  this  reason 
practically  all  kinds  of  wood  large  enough  to  make  a  post  are  used 
and  a  list  of  them  would  comprise  nearly  all  species  which  grow 
in  our  country.  Where  post  timber  is  scarce,  greater  care  is 
taken  in  selecting  the  kinds  of  wood  cut  into  posts,  and  in  any 
event  the  durable  species  are  almost  invariably  the  best  ones  to 
use.  Aside  from  the  question  of  cost,  which  is  always  of  first 
importance,  the  qualities  demanded  of  a  good  post  wood  are 
durability,  form,  and  ability  to  hold  staples  or  nails.  If  the  posts 
are  to  be  given  a  preservative  treatment,  their  ability  to  take 
treatment  must  also  be  considered. 

The  durability  of  posts  is  very  variable  even  when  cut  from  the 
same  kind  of  wood,  so  that  any  estimates  on  durability  must  be 
judged  with  considerable  latitude.  Posts  set  in  wet  ground  are 
more  durable  than  posts  set  in  soil  alternating  wet  and  dry. 
Posts  cut  from  slow-grown  trees  are  generally  more  durable  than 
posts  cut  from  rapid-grown  trees.  To  these  variations  must  be 
added  the  variations  due  to  climatic  conditions. 

The  best  formed  posts  come  usually  from  the  coniferous  trees 
like  cedar,  pine,  fir,  etc.,  and  fences  set  with  them  have  the  neat- 
est appearance.  Crooked  posts  are  more  liable  to  pull  the 
staples,  as  the  wires  fastened  to  them  are  not  in  alignment. 

In  general,  the  staple  or  nail-holding  power  of  a  post  varies 
with  its  dry  weight.  That  is,  posts  cut  from  heavy  woods  like 
locust,  oak,  etc.,  will  hold  staples  better  than  posts  cut  from  light 
woods  like  pine  and  cedar. 

If  the  posts  are  to  be  set  untreated,  the  more  heartwood  they 
contain  the  better.  Consequently,  split  posts  are  generally 
more  durable  than  round  posts.  If,  however,  a  preservative 
treatment  is  to  be  given,  round  posts  are  preferable,  as  the  sap- 

172 


PROLONGING  THE  LIFE  OF  FENCE  POSTS  173 

wood  can  be  more  easily  impregnated  than  the  heartwood  and 
a  continuous  layer  of  preserved  wood  will  then  extend  continu- 
ally around  the  post. 

Method  and  Time  of  Catting  Posts. — As  just  mentioned, 
split  posts  containing  mostly  heartwood  are  preferable  to  round 
posts  if  they  are  to  be  set  untreated.  So  far  as  possible,  the  ends  of 
the  posts  should  be  cut  with  an  axe  or  fine  saw,  especially  if  the 
posts  are  of  soft  wood.  A  smooth  cut  enables  rain  water  to  run 
off  more  freely  and  is  less  liable  to  cause  top  decay.  A  slight 
bevel  to  the  top  of  the  post  is  also  desirable  and  should  be  given. 
If,  however,  the  posts  are  subject  to  "frost  heave, "  that  is, 
thrown  out  of  alignment  by  frost,  the  bottoms  should  be  pointed 
so  they  can  be  reset  upright  in  the  spring  and  driven  into  the 
ground  with  a  mallet.  With  such  posts,  too  great  a  bevel  to 
the  top  should  be  avoided. 

It  is  generally  conceded  that  the  best  time  of  the  year  to  cut 
posts  is  in  winter  or  late  fall,  as  they  are  at  such  seasons  less 
sub j  ect  to  immediate  attack  by  fungi.  Furthermore,  sprouts  from 
winter-cut  stumps  are  far  more  vigorous  than  sprouts  from  stumps 
cut  in  spring  or  summer.  In  fact,  the  sprouting  capacity  of  a 
stump  may  sometimes  be  killed  by  summer  cutting. 

In  all  cases,  whether  treated  or  untreated,  posts  should  be 
peeled,  as  the  bark  offers  practically  no  protection  and  generally 
does  a  positive  harm.  All  bark  should  be  thoroughly  removed 
from  that  portion  of  the  post  to  be  treated  with  the  preservative 
so  that  the  preservative  can  have  an  opportunity  to  penetrate 
uniformly  into  the  wood. 

Method  of  Seasoning. — Whether  or  not  it  pays  to  season  posts 
which  are  to  be  set  untreated  is  still  an  open  question.  It 
appears,  however,  that  the  seasoning  adds  but  little  to  the  life 
of  the  posts  and  if  it  entails  much  delay  or  expense  is  not 
warranted. 

Of  course,  where  a  preservative  treatment  is  to  be  given, 
seasoning  is  as  a  rule  highly  advisable,  as  better  penetrations  are 
secured  and  the  protective  coating  is  less  subject  to  injury  due  to 
subsequent  checking.  A  simple  and  effective  means  of  season- 
ing posts  is  to  pile  them  in  horizontal  layers,  allowing  sufficient 
space  between  each  post  so  that  air  can  circulate  about  them. 
(See  Plate  XVII,  Fig.  C .)  If  the  posts  are  liable  to  check  seriously, 
as  in  the  case  of  the  gums  and  oaks,  it  is  best  to  pile  them 
closer  together  and  in  a  shady  place.  One  or  two  months  are 


174        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

generally  required  to  produce  an  air-dry  condition  but  in  warm 
weather  two  weeks  may  be  sufficient. 

Methods  of  Treatment  and  Their  Selection. — Farmers  are  the 
largest  consumers  of  posts,  and  most  of  them  make  their  own  posts. 
The  chief  requirement  for  a  preservative  treatment  is,  therefore, 
that  it  shall  be  one  which  the  farmer  can  give  himself.  In  some 
localities  where  the  posts  are  bought,  a  rather  elaborate  treat- 
ment can  be  given  and  the  posts  sold  in  a  treated  condition.  For 
the  most  part,  however,  the  most  practical  methods  are  those 
which  are  simple  of  execution.  The  ones  most  commonly  used 
are  described  below. 

Setting  Posts  in  Stones. — If  stones  are  abundant,  this  method  is 
better  than  setting  the  posts  directly  into  the  soil.  If  the  stones 
must  be  hauled  long  distances,  the  method  will  not  pay,  as  it 
does  not  materially  increase  the  life  of  the  posts.  Its  chief  ad- 
vantage lies  in  that  it  keeps  weeds  and  vegetation  away  from 
the  base  of  the  post,  thus  prolonging  its  life  and  protecting  the 
post  from  ground  fires. 

Setting  Posts  Upside  Down. — This  is  done  on  the  theory  that 
rain-water  will  run  out  of  the  post  more  readily  in  this  position 
than  when  set  large  end  down.  There  is  no  evidence  whatever 
to  substantiate  this  and  were  it  not  for  the  widespread  belief 
in  this  method  it  would  not  even  be  commented  upon  here. 
An  obvious  objection  to  this  method  is  that  it  places  the  small 
end  of  the  post  in  the  ground  and  hence  gives  a  weaker  post 
than  if  set  the  other  way,  since  greater  strength  and  resistance 
are  required  in  the  butt  than  in  the  top. 

Charring  the  Butt. — Charring  at  best  is  a  poor  method  of 
treatment,  since  its  effect  is  but  slight.  If  the  posts  are  charred 
they  should  first  be  air  seasoned  thoroughly  and  charred  from  the 
butt  to  about  6  inches  above  the  ground  line.  The  charr  should 
not  extend  more  than  1/4  inch  into  the  post.  While  this  treat- 
ment will  tend  to  increase  the  durability  of  the  post,  it  also 
weakens  it  at  the  very  point  where  it  needs  greatest  strength. 
However,  if  the  charring  can  be  done  at  slight  expense,  it  will 
more  than  pay  for  itself  through  added  durability. 

Dipping  in  Crude  Oil  and  Charring. — If  the  butt  ends  of  the 
posts  are  dipped  for  a  few  minutes  in  crude  oil  and  then  charred 
better  results  than  simple  charring  are  obtained.  (See  Plate 
XVIII,  Fig.  A.)  This  method  is,  however,  also  subject  to  criti- 
cism in  that  it  weakens  the  posts  at  the  butt.  It  seems  that 


PROLONGING  THE  LIFE  OF  FENCE  POSTS  175 

burning  the  posts  after  their  oil  treatment  tends  to  drive  some  of 
the  hot  oil  into  the  wood.  Some  experiments  made  along  this 
line  by  the  Wyoming  Experiment  Station  showed  pitch-pine 
posts  to  be  sound  after  16  years  of  service.  It  should  be  stated, 
however,  that  these  posts  set  untreated  under  similar  con- 
ditions would  last  at  least  12  years,  so  that  the  efficacy  of  the 
treatment  is  not  pronounced. 

Diagonal  Holes  Filled  with  Preservative. — This  method  of 
treatment  consists  in  boring  2  or  3  holes  about  1/2  inch  in 
diameter  and  3  inches  deep  diagonally  downward  into  the  post 
near  the  ground  line,  and  pouring  a  preservative  such  as  a  solu- 
tion of  copper  sulphate,  mercuric  chloride,  kerosene,  etc.,  into  the 
hole,  after  which  it  is  plugged.  When  the  preservative  escapes 
from  the  cavity,  the  plug  is  removed  and  more  inserted.  This 
treatment  is  not  recommended,  first  because  it  weakens  the  post, 
second  because  the  preservative  does  not  diffuse  evenly  through 
the  post  as  claimed,  and  third  because  the  results  secured  are  not 
sufficient  to  pay  for  the  trouble  and  expense  of  the  treatment. 

Brush  Treatments. — If  posts  are  first  air  seasoned  and  then 
given  two  coats  of  a  good  preservative  like  coal-tar  creosote  or 
carbolineum  in  the  manner  described  in  Chapter  V,  their  natural 
life  can  be  increased  from  3  to  6  years.  The  entire  butt  of  the 
post  should  be  treated  to  a  distance  about  1  foot  above  the 
ground  line.  The  preservative  had  best  be  applied  hot  and  worked 
into  the  cracks  as  completely  as  possible.  Brush  treatments 
when  properly  applied  will  more  than  pay  for  themselves  but  are 
not  as  efficient  as  can  be  given.  In  the  case  of  posts  that  decay 
at  the  top,  such  as  maple,  gum,  etc.,  it  is  well  also  to  brush-treat 
the  top. 

Dipping  Treatments. — These  are  more  effective  than  brush 
treatments,  as  the  preservative  is  sure  to  run  into  all  checks. 
As  posts  can  be  easily  handled,  this  method  is  recommended,  par- 
ticularly where  only  a  few  posts  are  to  be  treated.  Creosote  or 
a  similar  preservative  is  the  best  obtainable  for  dipping  treat- 
ments. All  that  is  necessary  is  to  have  the  preservative  hot 
(about  150°-180°  F.)  and  dip  the  butt  ends  of  the  post  in  a  tank 
or  barrel  containing  the  oil  for  about  1/4  minute,  after  which  they 
can  be  removed.  The  post  should  be  submerged  to  a  depth  of 
about  1  foot  above  the  ground  line.  One  dipping  will  give  good 
results.  Better  absorptions  and  penetrations  will  be  secured, 
however,  if  the  post  is  dipped  twice,  a  sufficient  time  elapsing 


176        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

between  treatments  to  allow  the  first  to  dry.  Tar  is  not  recom- 
mended for  either  brush  or  dipping  treatments. 

Impregnation  Treatments. — Treatments  of  this  kind  are  the 
best  known,  although  the  most  troublesome  and  expensive  to 
make.  If  the  preservative  selected  is  a  salt  like  zinc  or  mercuric 
chloride  or  copper  sulphate,  all  that  is  necessary  is  to  stand  the 
air-seasoned  posts  in  a  tank  or  vessel  containing  a  solution  of  the 
preservative.  For  zinc  chloride  a  6  percent  solution  is  recom- 
mended, while  for  copper  sulphate  1.5  percent  and  for  mercuric 
chloride  0.9  percent  is  sufficient.  If  the  latter  salt  is  used  great 
care  should  be  taken  in  handling  it  and  keeping  it  away  from  ani- 
mals because  of  its  very  poisonous  nature.  With  copper  and 
mercury  solutions,  wooden  or  stone  vessels  or  tanks  should  be 
used,  as  they  will  attack  iron.  The  posts  should  remain  standing 
in  the  preservative  for  about  1  week. 

Better  results  can  be  secured  with  coal-tar  creosote,  but  to  get 
most  effective  treatments  the  oil  should  be  heated  as  described 
in  Chapter  V.  If  but  one  tank  is  used,  the  oil  and  posts  can  be 
heated  and  then  allowed  to  cool  in  it.  This  cuts  down  the  num- 
ber of  posts  that  can  be  treated  per  day  and  is  called  a  "  single- 
tank  treatment."  If  two  tanks  are  used,  one  for  hot  oil  and  one 
for  cool  oil,  quicker  results  are  secured.  Such  treatments  are 
known  as  "  double-tank  treatments."  The  U.  S.  Forest  Service 
has  made  a  large  number  of  tests  in  treating  posts  by  these  meth- 
ods and  has  obtained  some  very  satisfactory  results.  These  are 
shown  in  Table  24. 

The  treating  tanks  necessary  to  treat  posts  in  this  manner 
and  the  method  of  operating  them  are  described  in  Chapter  V 
(open-tank  process). 

While  no  tests  that  have  been  made  are  known  to  the  author, 
it  is  believed  that  if  the  posts  are  boiled  in  crude  oil  or  any  cheap 
oil  for  2  or  3  hours  and  then  quickly  plunged  into  a  tank 
containing  a  solution  of  zinc  chloride,  copper  sulphate,  or  mer- 
curic chloride  at  atmospheric  temperature,  as  described  above, 
and  left  standing  in  this  solution  for  3  or  4  hours,  very 
good  results  will  be  secured  and  at  a  lower  cost  than  if  only  coal- 
tar  creosote  were  used.  It  is  quite  likely  that  green  posts  can 
be  treated  in  this  manner  and  good  penetrations  obtained,  but 
in  such  cases  the  length  of  the  boiling  period  will  probably  have 
to  be  increased  somewhat.  In  no  case  should  the  posts  be  heated 
above  275°  F. 


PROLONGING  THE  LIFE  OF  FENCE  POSTS 


177 


TABLE  24. — BEST   RESULTS   SECURED   IN   THE  TREATMENT  OF  VARIOUS 

WOODS1 
(All  posts  we^e  round,  peeled,  and  seasoned) 


Species 

Absorp- 
tiorr  creo- 
sote per 
5-inch 
post 

Perforation 

Single-tank  treatment 

Double-  tank 
treatment 

2  feet 
from 
butt 

2  feet 
from 
top 

Butt 

Top 

Hot 
oil 

Cold 
oil 

Hot 
oil 

Cool- 
ing oil 

Ash,  white  
Basswood  
Beech  
Birch,  river  
Butternut  

Cottonwood  

Gal. 

0.4 
0.6 
0.6 
0.6 
0.4 
(    0.4 
\    0.6 
0.6 
0.4 
0.6 
0.6 
0.6 
0.4 
0.6 
0.6 
0.6 
0.5 
0.4 
0.5 
0.6 
0.5 
0.5 
0.5 
0.5 
0.6 
0.6 
0.6 

In. 
0.4 
0.1 
1.0 
0.7 
0.56 
0.6 
0.3 
0.36 
0.46 
0.6 
0.6 
1.0 
0.5 
0.4 
1.0 
0.2 
1.06 
0.5 
.5 
.2 
.0 
.0 
.0 
0.5 
1.0 
0.4 
0.6 

In. 

0.05 
0.4 
0.3 

Hr. 
5 

Hr. 
12 

Dipped0.  . 

Hr. 

Hr. 

1 
1 
3 

i 
I 
1 

6 

}' 

6 
6 

12 
12 

Dipped0.  . 

e: 

li 

1 
H 

0.1 
0.1 

0.3 
0.3 
0.3 

Elm,  slippery  
Elm,  white  

12 

Gum,  black  
Gum,  cotton  (tupelo)  . 
Gum,  sweet  (red)  
Hickory,  bitternut.  .  .  . 
Magnolia,  sweet  (bay) 
Maple,  red  
Maple,  sugar  
Oak,  pin  
Oak,  red 

i 
i 
i 

1 
1 

i 

12 

Dipped0  .  . 

0.2 
0.3 
0.1 
0.5 
0.3 
1.0 
0.6 
0.3 
0.4 
0.3 
0.2 
0.2 
0.1 
0.2 

i 

4 
3 
1 
1 

li 
H 

3 
3 
3 
6 
1 
2 
4 

\ 

2 
2 
1 

f 

1 
1 
1 
2 
1 
12 
* 
* 
1 

Pine,  loblolly  
Pine,  lodgepole  
Pine,  pitch  
Pine,  scrub  
Pine,  shortleaf  
Poplar,  white  
Sycamore  
Tulip-tree  
Willow,  whitec  

a  Dipped  for  5  minutes  or  more. 

b  Width  of  sapwood.     Penetration  limited  by  impenetrable  heart. 

c  Requires  especially  thorough  seasoning. 

Pitch  Streaks. — It  is  well  known  that  pine  posts  which  contain 
large  amounts  of  resin  are  more  durable  than  pine  posts  which  are 
not  resinous.  This  fact  is  taken  advantage  of  in  certain  portions 
of  the  South  by  peeling  all  of  the  bark  off  a  small  tree  to  a  height 
of  7  or  8  feet  except  for  a  strip  about  2  inches  wide,  which  is 
sufficient  to  keep  the  tree  alive  for  several  years.  The  tree 
thus  injured  covers  its  wound  with  resin,  which  frequently 
penetrates  into  the  wood  for  a  half  inch  or  more  and  thus 
forms  pitchy  wood.  In  two  or  more  years  the  tree  is  felled  and 
the  post  cut  from  it.  This  method  is  not  recommended,  as  it 
is  very  destructive  to  timber  and  wasteful,  and  the  posts  are 

'Farmers'  Bulletin  387,  U.  S.  Department  of  Agriculture. 
12 


178        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

very  liable  to  catch  on  fire,  if  ground  fires  are  common,  because 
of  the  pitchiness  of  the  wood. 

Cost  of  Treatment. — Costs  of  treatment  will  be  estimated 
only  for  brush,  dipping,  and  impregnation  treatments,  as  the 
other  treatments  described  cost  practically  nothing  except  for 
labor,  which  is  generally  supplied  by  the  farmer  himself  at  odd 
times.  If  labor  is  included,  the  cost  of  the  treatments  will,  of 
course,  depend  upon  the  number  of  posts  which  can  be  treated 
per  day  and  the  value  the  farmer  puts  upon  his  labor.  In  the 
following  calculations  it  is  assumed  that  the  apparatus  used  is 
such  as  is  described  in  Chapter  V  and  that  the  price  paid  for  the 
chemicals  is  average  for  small  quantities,  viz.,  creosote  2  cents 
per  pound,  zinc  chloride  5  cents  per  pound,  copper  sulphate 
6  cents  per  pound,  and  mercuric  chloride  70  cents  per  pound; 
these  being  used  in  the  manner  specified  above.  The  total  cost 
of  treatments  per  post  (6-inch  top  7  feet  long)  will  then  be 
about  as  estimated  in  Table  25. 

TABLE  25. — ESTIMATED  COST  OF  TREATING  FENCE  POSTS  (BUTT  ONLY) 


Method  of  treatment 

Total  cost  per 
post  (cents) 

Brush-  treated  coal-tar  creosote.     .             

4-6 

Dipped,  coal-tar  creosote 

5-7 

Impregnated  with  zinc  chloride,   copper  sulphate  or 
mercuric  chloride 

3-7 

Impregnated  with  coal-tar  creosote  

12-20 

If  the  entire  post  is  treated  the  above  costs  will  be  about  doubled. 

Economy  of  Treatment. — As  the  preservative  treatment  of 
fence  posts  cut  from  durable  wood  is  unnecessary,  it  will  be 
assumed  that  only  posts  having  a  comparatively  short  natural 
life  will  be  given  a  treatment.  In  order  to  approximate  the  value 
of  the  treatments,  therefore,  we  will  take  as  an  example  posts 
cut  from  such  woods  as  red  oak,  maple,  pine,  etc.,  which  decay 
in  about  5  years  and  which  are  worth  about  5  cents  each.  The 
cost  of  setting  the  posts  will  be  estimated  at  12  cents  each.  With 
these  assumptions  and  figuring  interest  compounded  at  6  percent, 
the  annual  cost  of  posts  treated  by  the  various  methods  will  be 
as  shown  in  Table  26. 

It  will  be  noted  that,  if  the  values  given  in  the  table  are  approxi- 
mately correct,  the  economy  resulting  from  the  treatment  of 
posts  is  not  great.  The  selection  of  woods  to  be  cut  into  posts 
is  perhaps  of  as  great  or  even  greater  importance.  For  this 


PROLONGING  THE  LIFE  OF  FENCE  POSTS 


179 


TABLE  26. — ESTIMATED  ANNUAL  CHARGES  OF  TREATED  POSTS  (BUTT 
TREATED  ONLY) 


Method  of  treatment      —  . 

Life  of 
post 
(years) 

Cost  of  post 
set  in  position 
(cents) 

Annual 
charges 
(cents) 

Untreated          

5 

17 

4.0 

Brush  treated  coal-tar  creosote.  . 

9 

22 

3.2 

Dipped  coal-tar  creosote 

11 

23 

2  9 

Impregnated  with  zinc  chloride,  copper 
sulphate,  or  mercuric  chloride  

12 

22 

2.6 

Impregnated  with  coal-tar  creosote  

21 

33 

2.8 

reason,  Table  27  is  given  to  show  what  can  be  expected  from 
posts  cut  from  a  variety  of  woods.  Fortunately,  some  reliable 
data  from  actual  experience  is  available  on  the  life  of  untreated 
posts,  this  data  being  compiled  from  painstaking  inquiries  and 
researches  by  Mr.  J.  J.  Crumby  of  the  Ohio  Agricultural  Ex- 
periment Station  and  published  by  him  as  Bulletin  No.  219  of 
that  station.  He  examined  292  fences  containing  30,160  posts 
in  Ohio,  Indiana,  Illinois,  Kansas,  and  Texas.  The  results  are 
shown  in  Table  27. 

TABLE  27. — LIFE  OF  FENCE  POSTS  SET  UNPROTECTED 


Kind  of  wood 

Average  age 
pf  fences 
(years) 

Percent  of 
sound  posts  at 
this  age 

Osage  orange  

33  2 

99 

Locust  (black) 

25  4 

82  3 

Red  cedar  

33.2 

65.3 

Mulberry  

23  8 

74.1 

White  cedar. 

18  4 

68 

Catalpa  

17.5 

61.8 

Chestnut  

12.3 

71  8 

Oak  (mostly  white). 

11  8 

65  2 

Black  ash  

6.5 

64.2 

It  can  be  seen  at  a  glance  that  posts  cut  from  such  durable 
woods  as  osage  orange,  black  locust,  red  cedar,  etc.,  will  far  out- 
last nondurable  posts  treated  by  the  best  methods  known  and 
will  be  far  cheaper  to  use  even  if  they  cost  considerably  more. 

The  following  interesting  facts  on  the  life  of  untreated  fence 
posts  are  brought  out  by  Mr.  Crumley's  investigation: 

1.  "A  large  post  usually  lasts  longer  than  a  small  one  of  the 
same  wood. 

2.  There  is  no  difference  which  end  is  put  in  the  ground,  except 
that  the  sounder  or  larger  end  should  have  the  preference. 


180        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

3.  In  stiff  clay  soil,  the  posts  rot  principally  just  beneath  the 
top  of  the  ground,  and  in  a  porous,  sandy,  or  gravelly  soil  they 
usually  rot  from  the  top  of  the  soil  all  the  way  down. 

4.  In  soil  that  is  full  of  water  all  the  time,  posts  will  last 
longer. 

5.  Timber  that  grows  rapidly  and  in  the  open  is  not  as  good  as 
the  same  variety  that  grows  in  the  woods. 

6.  There  is  some  evidence  that  it  is  not  a  good  time  to  cut  posts 
just  as  the  tree  begins  to  grow  in  early  spring. 

7.  The  wood  at  the  center  of  the  tree  is  not  as  good  as  that  just 
inside  the  sapwood.     This  characteristic  is  very  common  with 
nearly  all  the  varieties  of  timber  examined,  especially  so  with  the 
locust,  white  cedar,  hardy  catalpa,  and  the  oaks." 


CHAPTER  XI 

PROLONGING  THE  LIFE  OF  PILING  AND  BOATS  FROM 
DECAY  AND  MARINE  BORERS 

To  satisfactorily  treat  piling  and  timber  placed  in  salt  water 
where  marine  borers  abound  is  exceedingly  difficult  of  accomplish- 
ment and  the  problem  is  quite  different  from  that  of  protecting 
timber  from  decay.  As  has  been  pointed  out  in  Chapter  II, 
it  matters  little  what  the  wood  is,  for  the  borers  will  rapidly 
perforate  it.  The  hardest  woods  like  oak  and  eucalyptus  are  at- 
tacked by  them.  The  most  resistant  wood  k'nown  against  these 
attacks  is  the  greenheart,  but  even  this  will  eventually  succumb. 

Of  course  piling  driven  in  fresh  water  or  in  the  ground  is  not 
subject  to  the  attack  of  marine  borers.  If  such  piling  is  kept 
continuously  submerged  or  buried,  no  preservative  treatment  is 
necessary,  as  it  will  last  indefinitely.  If,  however,  parts  of  it 
project  into  the  air,  decay  will  take  place  and  some  preservative 
treatment  is  advisable.  The  methods  described  under  the 
treatment  for  poles  may  be  considered  in  this  connection,  except 
of  course  if  the  piling  is  in  water  or  wet  soil  soluble  salts  should 
not  be  used. 

Selection  of  Species. — A  good  pile  timber  should  be  straight, 
strong,  susceptible  to  treatment,  and  of  moderate  cost.  Any 
wood  which  has  these  properties  can  be  used  to  advantage. 
These  requirements  are  admirably  filled  by  our  common  southern 
pines,  the  loblolly,  shortleaf,  longleaf,  and  Cuban.  On  the 
Pacific  Coast,  western  yellow  pine  and  Douglas  fir  are  available, 
although  the  latter  is  objectionable  on  account  of  its  resistance 
to  treatment  by  present  known  processes.  Strange  to  say,  two 
woods  which  differ  greatly  in  their  mechanical  properties  are  used 
untreated  for  piling  with  apparent  good  results.  These  are  the 
palmetto,  which  is  comparatively  weak  and  " spongy,"  and 
greenheart,  which  is  exceedingly  strong  and  dense.  The  re- 
sistance of  the  palmetto  is  supposed  to  be  due  to  its  porous  nature 
and  the  natural  adversion  of  the  teredo  to  crossing  vacant  spaces. 
The  greenheart  apparently  has  some  peculiarity  not  at  present 
understood  which  is  unattractive  to  the  marine  borers. 

181 


182        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

If  the  piling  is  to  be  used  in  waters  where  attack  by  marine 
borers  is  known  to  be  very  rapid,  only  those  woods  which  have 
a  wide  sapwood  (about  2  inches  in  width)  should  be  used,  as  more 
preservative  can  be  forced  into  them  and  better  results  thus 
secured.  Where  attack  is  less  severe,  it  seems  that  piling  with 
sapwood  about  1  inch  wide  is  preferable,  as  this  tends  to  con- 
centrate the  oil  in  the  outer  portion  to  a  greater  extent  than  when 
the  sapwood  is  wide.  In  either  case  it  appears  that  a  con- 
centration (heavy  injection)  of  oil  is  better  than  diffusing  the 
same  amount  of  oil  more  deeply  through  the  wood — a  condition 
quite  the  reverse  of  the  protection  against  fungi. 

The  Manufacture  of  Piling. — In  making  piling  which  is  to  be 
treated  there  are  two  essentials  which  should  be  strictly  adhered 
to.  First,  is  a  complete  removal  of  all  bark  from  that  portion 
of  the  pile  which  will  project  above  the  mud  line.  Bark  is  very 
resistant  to  penetration  and  if  thin  strips  of  it  are  left  adhering 
to  the  wood  the  penetration  under  such  strips  may  be  very  slight 
or  none  at  all;  consequently,  no  matter  how  well  the  rest  of  the 
pile  may  be  treated,  attack  will  begin  at  these  points  and  extend 
rapidly  to  the  interior.  Many  failures  have  occurred  because 
this  simple  rule  was  violated.  (See  Plate  XVIII,  Fig.  B.) 

The  second  precaution  is  to  keep  the  sapwood  continuous 
and  not  cut  into  it  so  as  to  expose  the  heartwood  at  any  point 
which  can  be  reached  by  the  marine  borers.  Heartwood  does  not 
take  treatment  as  well  as  sapwood,  and  is  always  more  subject 
to  attack  no  matter  how  well  the  treatment  is  given.  As  that 
portion  of  the  pile  which  is  driven  below  the  mud  line  is  not 
subject  to  attack  either  by  decay  or  marine  borers,  and  hence 
will  last  indefinitely,  it  is  believed  that  much  economy  in  the 
treatment  of  piling  could  be  effected  by  leaving  the  inner  bark 
adhering  to  this  portion  of  the  pile.  In  this  way,  much  less 
oil  would  be  consumed  without  in  any  way  affecting  the  life  of 
the  pile. 

Methods  of  Seasoning. — If  the  piling  can  be  air  seasoned  with- 
out decay,  the  method  followed  is  the  same  as  that  given  for  air- 
seasoning  poles.  Unfortunately,  it  often  happens  that  this  can 
not  be  done,  particularly  in  the  South  where  the  air  is  warm  and 
damp  and  decay  is  liable  to  occur  before  the  pile  becomes  dry. 
Some  plants  store  their  piling  in  water  prior  to  treatment  or  leave 
them  on  the  ground.  Both  these  methods  may  become  ob- 
jectionable in  that  they  may  cause  marked  differences  in  the 


PLATE  XVIII 


FIG.  A. — Fence  posts  dipped  in  crude  oil  and  then  charred.     Note  good 
condition  after  12  years'  service.     (Photo  courtesy  of  the  Wyoming  Exp. 

Station.) 


FIG.  B. — Sections  of  creosoted  piling.     Note  erratic  penetrations  of  creosote. 

(Forest  Service  photo.) 

(Facing  page  182.) 


PLATE  XVIII 


FIG.  C. — Pile  sheathed  with   zinc  entirely  destroyed  by  marine  borers, 
Pensacola,  Fla.     (Forest  Service  photo.) 


FIG.  D. — Piling  protected   with   cement   casings  from   attack   by   marine 
borers,  Pensacola,  Fla.     (Forest  Service  photo.) 


POLONGING  THE  LIFE  OF  PILING  AND  BOATS          183 

water  content  of  the  pile,  which  in  turn  is  liable  to  result  in 
unequal  penetrations. 

When  air  seasoning  is  impossible,  live  steam  or  oil  seasoning 
can  be  used.  The  methods  "of  doing  this  have  been  given  in 
Chapter  IV.  Care  should  be  taken  not  to  use  temperatures 
above  275°  F.,  as  injury  to  the  timber  is  liable  to  occur.  The 
length  of  time  the  wood  should  be  steamed  or  boiled  varies  con- 
siderably, depending  upon  the  size  and  " greenness"  of  the 
wood  and  the  amount  of  preservative  to  be  injected.  In  general, 
it  is  between  6  and  18  hours,  although  longer  periods  are  some- 
times used. 

Methods  of  Treatment  and  Their  Selection. — Many  methods 
for  treating  piling  have  been  tried  but  only  a  few  have  been  found 
meritorious.  Only  those  which  have  been  most  commonly 
practised  are  described. 

Bark  Left  on  the  Piles. — Bark  resists  the  attacks  of  the  marine 
wood  borers,  but  will  adhere  only  a  short  time,  after  which  it 
loosens  and  falls  off.  If  the  piles  are  to  be  driven  untreated, 
however,  the  bark  should  be  left  on,  except  for  the  portion  pro- 
jecting above  high- water  level. 

Plank  Coating. — Strips  of  wood  nailed  tightly  together  around 
the  pile  will  ward  off  attack  for  a  short  period,  but  their  value  is 
only  temporary. 

Nail  Coating. — Flat-headed  nails  resembling  upholsterers 
tacks  driven  into  the  pile  close  together  will  prolong  the  life 
of  the  pile.  It  seems  that  the  iron  rust  formed  by  the  nails  is 
avoided  by  some  of  the  marine  borers,  especially  the  limnoria. 
The  method  is,  however,  expensive  and  awkward  and  not 
recommended. 

Metal  Coating. — Sheets  of  zinc  or  copper  nailed  around  the 
pile  at  those  points  subject  to  borer  attacks  will  effectively  pro- 
tect the  pile  as  long  as  they  last.  (See  Plate  XVIII,  Fig.  C.) 
Care  should  be  taken,  however,  to  make  all  joints  tight.  The 
coating  'will  corrode  in  time  and  is  liable  to  puncture  by  floating 
debris,  but  this  method  of  treatment  is  efficacious. 

Burlap  Coatings. — These  are  made  by  coating  the  pile  where  it 
is  subject  to  attack  with  various  mixtures  such  as  coal-tar,  pitch, 
asphaltum,  sand,  etc.,  and  wrapping  the  whole  in  several  layers  of 
burlap.  Very  good  results  have  been  secured  from  treatment 
of  this  kind. 


184       THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Cement  Casings.1 — These  are  made  in  two  ways,  (1)  with 
no  space  between  the  casing  and  the  pile,  and  (2)  with  an  inter- 
vening space  of  from  2  to  4  inches. 

The  first  are  manufactured  as  follows :  The  bark  and  knots  are 
removed  and  the  pile  driven.  A  jacket  of  iron,  wood,  or  sewer 
pipe  is  placed  around  it,  and  the  space  between  jacket  and  pile, 
which  is  from  2  to  4  inches  wide,  is  filled  with  hydraulic  cement. 
(See  Plate  XVIII,  Fig.  D.)  When  this  becomes  hard,  the 
jacket  is  removed.  Some  jackets  are  so  made  that  they  can  be 
applied  to  the  pile  without  disturbing  the  superstructure  of  the 
wharf,  thus  making  repairs  to  broken  casings  easy. 

The  second  class  is  composed  of  cement  pipes  divided  longitu- 
dinally into  two  halves,  which,  when  placed  together  around 
the  pile,  are  joined  by  a  scarf  joint  keyed  with  a  wooden  plug 
soaked  in  hot  tar.  The  intervening  space  between  pile  and  casing 
is  filled  with  sand.  The  chief  advantage  of  this  kind  of  casing 
is  the  fact  that  broken  sections  can  easily  be  replaced  without 
removing  the  superstructure  of  the  wharf.  These  treatments 
are  very  efficient. 

Electrolysis. — A  canvas  bag  or  curtain  is  placed  around  the 
pile  driven  in  position  and  an  electric  current  passed  through  the 
pile  and  the  surrounding  water.  This  liberates  chlorine  gas  in 
the  salt  water  and  kills  the  borers  in  the  pile.  It  is  necessary, 
of  course,  to  apply  this  treatment  from  time  to  time,  since  it 
simply  kills  the  borers  present  in  the  wood.  The  treatment  is 
expensive,  but  performs  a  peculiar  function  in  being  able  to  pro- 
tect piles  already  set  in  position  and  undergoing  attack. 

Impregnation  with  Coal-tar  Creosote. — For  general  work, 
treatments  with  coal-tar  creosote,  by  either  the  Bethell  or 
Boiling  process  (see  Chapter  V  for  details  of  treatment),  have 
given  most  effective  results.  It  is  necessary,  however,  to  inject 
large  quantities  of  the  oil  into  the  wood  (18  to  24  pounds  per  cubic 
foot)  if  the  piles  are  subject  to  severe  attack.  This  greatly 
increases  the  cost  of  the  treatment.  However,  piles  properly 
treated  in  this  manner  have  been  known  to  last  for  30  years, 
while  untreated  piles  set  in  similar  waters  are  completely  de- 
stroyed in  5  years.  While  this  method  of  treatment  is  the  best 
known,  it  leaves  much  to  be  desired.  It  is,  as  has  just  been 
stated,  very  costly.  Furthermore,  several  cases  have  been  called 
to  the  author's  attention  where  the  piling  so  treated  has  not 

1  Circular  128,  U.  S.  Forest  Service. 


PROLONGING  THE  LIFE  OF  PILING  AND  BOATS        185 

withstood  attack,  especially  of  the  limnoria  and  xylotria,  and 
failed  in  less  than  8  years-,  after  it  was  driven.  There  is  a 
distinct  need  for  a  good  preservative  which  can  be  used  in 
treating  piling  set  in  water^'badly  infected  with  marine  borers. 
(See  Plate  XIX,  Figs.  A  and  B.) 

It  seems  that  a  more  economical  method  of  treatment  than 
is  now  practised  could  be  devised.  As  has  already  been  pointed 
out,  that  portion  of  the  pile  driven  below  mud  line  needs  no  pro- 
tection, yet  in  present  methods  it  receives  even  more  oil  than 
the  rest.  Furthermore,  the  portion  of  the  pile  above  high-water 
mark  does  not  require  as  heavy  injection  as  that  portion  in  the 
water.  If  a  plant  could  be  constructed  which  could  be  tilted 
vertically  after  the  piles  are  run  into  it,  and  only  a  portion  of 
the  pile  impregnated,  it  is  believed  much  expense  could  be  saved. 
Such  a  plant  would  also  be  admirable  for  butt-treating  poles 
under  pressure. 

The  selection  of  the  process  to  be  used  in  treating  piles  largely  de- 
pends upon  local  conditions.  If  the  waters  are  comparatively  free 
from  borers,  such  as  in  our  more  northern  harbors  on  the  Atlantic 
Coast,  or  if  the  waters  are  brackish,  a  comparatively  light  treat- 
ment with  creosote  (10  to  14  pounds  per  cubic  foot)  is  sufficient. 
If,  however,  the  borers  abound  as  at  Gulfport;  Miss.,  and  San 
Francisco,  Cal.,  the  heaviest  impregnations  should  be  used. 
Where  the  piling  can  be  protected  from  floating  debris,  casings 
of  cement  or  metaljas  described  above  are  also  effective.  These 
can  also  be  placed  over  piling  already  driven  into  position  if  it  is 
found  attack  is  taking  place.  Treatments  with  burlap,  soaked 
as  already  described,  give  good  results  even  in  waters  badly 
infected.  So  far  as  is  at  present  known,  heavy  impregnations 
with  coal-tar  creosote  are,  when  all  things  are  considered,  the 
most  effective  that  can  be  given,  and  they  are  recommended  for 
all  places  where  attack  is  severe. 

Cost  of  Treating  Piling. — The  total  cost  of  treating  piling  by 
the  standard  full- cell  creosote  process  including  the  removal  of 
the  strips  of  inner  bark  or  ''skin"  left  after  the  piles  have  been 

TABLE  28. — ESTIMATED  COST  OF  TREATING  PILING  WITH 
CREOSOTE 


Item 

Per  cubic  foot  (cents) 

Cost  of  peeling  and  handling  at  plant  
Cost  of  preservative  

1.0-2.5 
16  5 

Cost  of  treatment  

3  5-6  0 

Total  cost  of  treatment  

21.0-25.0 

186       THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

roughly  peeled  in  the  woods  is  given  in  Table  28,  where  oil  is 
figured  at  9  cents  a  gallon  of  8.75  pounds,  the  piles  are  steam- 
seasoned,  and  16  pounds  of  oil  per  cubic  foot  are  injected. 

Economy  in  Treating  Piling. — The  cost  of  treating  and  driving 
piling  as  well  as  the  life  secured  from  it  are  all  so  variable  that 
general  figures  are  of  value  only  as  an  illustration.  In  prepar- 
ing the  general  estimates  given  in  Table  29,  two  conditions 
are  illustrated,  case  (A)  where  piling  is  driven  in  salt  water 
where  attack  by  marine  borers  is  light,  and  case  (B)  where 
attack  is  severe.  In  the  former  it  is  assumed  that  a  treatment 
of  16  pounds  of  creosote  per  cubic  foot  is  given,  while  in  the  latter 
22  pounds  are  injected.  The  cost  of  driving  the  piling  including 
the  superstructure  bolted  to  them  is  taken  as  $6  per  pile,  and  all 
piles  are  assumed  to  be  40  feet  in  length  and  to  contain  about 
25  cubic  feet  each.  Variations  of  at  least  100  percent  in  the 
estimated  annual  savings  either  way  can  be  expected  because 
of  the  extremely  varying  conditions  under  which  piling  is  used. 

TABLE  29. — ESTIMATED  ECONOMY  IN  TREATING  PiLiNG1 


Item 

Case  A 

Case  B 

Life  of  untreated  piling  —  years  

8 

3 

Life  of  treated  piling  —  years  
Cost  of  untreated  piling  —  driven  in  place  

25 

$8.50 

18 
$8.50 

Cost  of  treated  piling  —  driven  in  place  
Annual  charge  —  untreated  piling.  . 

$14.75 
$1.32 

$16.50 
$3.12 

Annual  charge  —  treated  piling  
Annual  saving  —  treated  over  untreated  

$1.03 
$0.29 

$1.40 

$1.72 

The  Preservative  Treatment  of  Wooden  Boats. — If  wooden 
boats  are  used  in  salt  water  which  contains  marine  borers,  they 
are  very  subject  to  attack  and  unless  properly  protected  their 
bottoms  may  be  entirely  destroyed  in  a  year  or  less.  For  light 
boats  which  can  be  readily  hauled  out  of  the  water,  repeated 
coatings  with  copper  paint  will  prove  effective.  Heavier  boats 
should  be  protected  with  sheet  copper  nailed  securely  to  the 
bottom.  Barges  and  similar  craft  should  have  their  bottoms 
built  of  lumber  heavily  creosoted,  12  or  more  pounds  per  cubic 
foot  being  injected.  Even  under  these  conditions,  attack  is  very 
liable  to  occur.  If  fresh-water  moorings  are  accessible  the  borers 
in  the  boats  can  be  killed  by  anchoring  the  boats  for  a  few  days 
in  fresh  water. 

1  Interest  compounded  annually  at  5  percent. 


PLATE  XIX 


FIG.  A. — Sections  of  longleaf  pine  piles  after  21  months'  exposure  to  the 
attack  of  marine  borers  at  Gulf  port,  Miss.  Section  to  the  right,  untreated; 
section  to  the  left,  impregnated  with  a  crude  oil.  (Forest  Service  photo.) 

(Facing  page  186  ) 


PLATE  XIX 


o    «.  .   «-    c 


FIG.  B. — Untreated  pine  piles  completely  destroyed  by  marine  wood  borers, 
Santa  Rosa  Island,  Fla.     (Forest  Service  photo.) 


PROLONGING  THE  LIFE  OF  PILING  AND  BOATS         187 

Wood  in  boats  not  subject  to  attack  by  borers  is  often  quickly 
decayed,  as  the  moist ^conditions  of  the  air  in  them  is  very 
favorable  to  the  growth  of  fungi.  It  is  a  very  good  plan  to  brush- 
treat  with  creosote  or  carftolineum  all  such  joints  subject  to 
decay.  The  author  has  had  considerable  experience  in  protecting 
small  fresh- water  boats  in  this  manner  and  has  entirely  eliminated 
decay.  Of  course,  the  portions  so  treated  cannot  be  painted, 
as  paint  will  not  adhere  to  the  creosoted  wood.  In  barges  and 
boats  where  artistic  effects  are  not  essential,  all  lumber  subject 
to  decay  can  be  profitably  creosoted  by  one  of  the  empty-cell 
methods.  This  will  protect  the  wood  from  rotting  without 
increasing  its  weight  very  materially. 

Although  no  cases  are  known  of  where  it  has  been  tried,  it  is 
believed  that  the  life  of  small  pleasure  boats  subject  to  decay 
can  be  materially  prolonged  if  they  are  filled  in  the  spring  with  a 
3  percent  solution  of  copper  sulphate  or  a  1  percent  solution  of 
mercuric  chloride  and  allowed  to  soak  in  this  solution  for  several 
days  before  they  are  run  into  the  water.  These  solutions  should 
soak  into  the  joints  and  permeate  the  partially  decayed  wood, 
thus  killing  whatever  fungi  might  be  present. 


CHAPTER  XII 
PROLONGING  THE  LIFE  OF  MINE  TIMBERS 

On  account  of  the  warm  damp  air  which  exists  in  many  mines, 
timber  placed  in  them  is  very  subject  to  attack  by  decay  and  in- 
sects. As  the  methods  which  will  eliminate  decay  will  also  elimi- 
nate insects,  no  differentiation  in  treatment  is  specified.  It  is 
very  common  for  mine  timbers,  a  foot  or  more  in  thickness,  to 
become  completely  decayed  in  less  than  2  years  if  set  untreated. 
The  expense  of  resetting  these  timbers  is  great,  and,  furthermore, 
such  replacements  generally  interfere  with  the  working  of  the 
mine.  This  is  particularly  true  in  coal  and  iron  mines.  In 
many  mines  the  walls  are  of  solid  rock  so  that  little  timber  is  neces- 
sary, and  even  this  is  often  not  subject  to  rapid  decay.  Also,  in 
temporary  workings,  where  the  props  are  either  left  standing  or 
"pulled"  after  the  coal  or  ore  has  been  removed,  a  preservative 
treatment  is  unnecessary.  But  for  permanent  shafts  and 
gangways  it  is  highly  advisable  to  so  treat  the  timbers  that 
greatest  life  can  be  secured  from  them  and  thus  the  working  of 
the  mine  will  be  least  interfered  with.  Several  mine  com- 
panies in  the  United  States  are  using  treated  timber  and  have 
secured  excellent  results.  As  the  workings  are  extended  deeper 
and  deeper,  the  need  for  a  preservative  treatment  is  found 
to  become  more  acute. 

Selection  of  Species. — It  is  the  practice  at  most  mines  to  use 
any  kind  of  wood  which  is  available  and  is  large  enough  for  the 
purpose  desired.  Preference  is,  of  course,  given  to  those  varieties 
which  are  most  durable.  This  freedom  in  the  selection  of 
species  must  be  considered  bad  practice  on  the  part  of  the  mine 
operator,  for  aside  from  the  large  expense  and  trouble  to  which 
he  is  put  in  replacing  the  decayed  timber,  he  is  filling  his  mines 
with  the  mycelia  of  the  destructive  fungi.  Sanitation  of  timber 
in  such  conditions  is  advisable  if  contamination  is  to  be  pre- 
vented, just  as  it  is  among  human  beings  where  some  are 
affected  with  a  contagious  disease. 

Strength,  form,  and  durability  are  the  inherent  properties 

188 


PROLONGING  THE  LIFE  OF  MINE  TIMBERS  189 

required  of  a  good  mine  timber,  but  if  a  preservative  treatment  is 
to  be  given,  adaptability  to  treatment  can  be  substituted  for 
natural  durability.  As  mine  timbers,  except  for  shafting  and 
"  long  walls,"  are  generally  *hort,  they  are  not  so  difficult  to  fur- 
nish as  timber  for  poles  and  piles,  and  consequently  the  mine 
operator  has  a  wider  choice  of  species  at  his  command.  If  the 
timbers  are  to  be  set  untreated,  durable  woods  should  be 
selected  for  the  permanent  workings,  such  as  osage  orange, 
black  locust,  white  oaks,  chestnut;  or  if  strength  is  not  so 
important,  the  cedars,  cypress,  etc.  The  more  heartwood  they 
have  the  longer  will  be  the  life  secured. 

When  treated,  the  red  oak,  maple,  birch,  beech,  the  hard 
pines,  fir,  elm,  etc.,  are  good  woods  where  great  strength  is 
required,  and  for  workings  requiring  less  strength  most  any  wood 
having  an  inch  or  more  of  sapwood  can  be  used  to  advantage. 

The  Manufacture  of  Mine  Timbers. — In  permanent  workings, 
whether  the  timbers  are  to  be  set  treated  or  untreated,  they 
should  be  peeled  before  they  are  placed  in  the  mine.  This  in 
itself  will  increase  their  durability  and  destroy  the  breeding  places 
for  many  wood-destroying  insects.  To  peel  timber  in  the  woods 
or  at  the  shipping  point  effects  a  saving  in  freight  and  in  the  cost 
of  handling.  The  weight  of  the  bark  usually  amounts  to  from 
6  to  15  percent  of  the  original  green  weight.  If  the  timbers  are 
to  be  treated,  they  should  be  framed  to  exact  dimensions  so  that 
no  cutting  into  the  treated  surface  will  be  necessary.  Unless 
there  is  some  good  reason  to  the  contrary,  all  timbers  intended 
for  treatment  should  be  left  round.  Slabbing  them  only  exposes 
the  heartwood  and  hence  decreases  the  effectiveness  of  the 
treatment. 

Methods  of  Seasoning. — When  mine  timbers  are  set  untreated 
there  is  little  or  no  advantage  gained  in  seasoning  them  before  plac- 
ing them  in  the  mine.  If  they  are  to  be  treated,  however,  season- 
ing is  advisable,  as  it  enables  better  results  to  be  secured.  Air 
seasoning  is  recommended,  unless  for  some  local  reason  it  can- 
not be  practised.  Props  and  other  round  timbers  can  be  piled 
on  skids  in  the  same  manner  as  poles  (see  Chapter  IX).  Mine 
ties  can  be  piled  like  railroad  ties  (see  Chapter  VIII).  Lumber 
and  sawed  stock  should  be  piled  with  liberal  air  courses  be- 
tween the  planks,  and  with  as  small  an  area  as  possible  in  contact. 
The  rules  as  given  in  Chapter  IV  for  the  selection  and  care  of  the 
seasoning  yard  should  be  followed. 


190        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


The  length  of  time  necessary  to  air  season  the  timbers  of  course 
varies  considerably  (see  Chapter  IV).  In  general,  1  or  2 
months  are  sufficient.  Fig.  23  shows  the  rate  at  which  loblolly 
pine  and  red  oak  props  and  ties  air-seasoned^in  Pennsylvania  and 
Alabama.  Whenever  possible,  timber  should  be  seasoned  before 
shipment,  as  a  considerable  saving  in  freight  will  result.  If  it  is 
not  practicable  to  air  season  the  timber,  it  can  be  seasoned  in 
steam  or  oil  as  described  in  Chapter  IV.  The  length  of  time  nec- 
essary to  do  this  will,  of  course,  vary  with  each  kind  and  form  of 


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05  10          15          20  25          30          35          40          45          50          55 

Days  Seasoned 

FIG.  23. — Percentage  of  green  weight  lost  by  seasoning  mine  timbers. 

timber  and  with  the  character  of  treatment  desired,  so  that  each 
plant  will  have  to  work  out  its  own  best  operative  conditions. 
The  instructions  already  given  in  Chapters  IV  and  V  should  be 
consulted  for  helpful  suggestions. 

METHODS  OF  TREATMENT  AND  THEIR  SELECTION 

Mine  Ties. — The  methods  of  treating  mine  ties  do  not  differ  in 
any  essential  way  from  the  treatment  of  cross-ties  described 
in  Chapter  VIII.  If  the  mines  are  dry,  treatments  with  zinc 
chloride  or  any  empty-cell  treatment  with  creosote  will  prove 
very  satisfactory.  On  the  other  hand,  if  the  ties  are  liable 
to  be  wet  or  alternately  dry  and  wet,  heavier  injections  of 

1  From  Bulletin  107,  United  States  Forest  Service. 


PROLONGING  THE  LIFE  OF  MINE  TIMBERS  191 

creosote  are  best.  Ties  constantly  in  water  need  no  treatment 
whatever. 

Mine  Props. — Under  tin's"  heading  are  included  props,  legs, 
collars,  and  caps.  The  cheapest  treatment  consists  in  brush- 
treating  these  with~coal-tar  creosote,  and  if  the  preservative  is 
applied  to  the  ends  and  joints  as  well  as  the  sides,  several  years 
increase  in  life  will  be  secured,  so  that  the  cost  of  the  opera- 
tion will  more  than  pay  for  itself.  Such  treatments  should, 
of  course,  be  applied  to  the  timbers  before  they  are  placed 
in  the  mine.  If  dipped,  better  results  will  be  secured  than 
by  brush-treating,  as  all  checks  will  be  coated  with  the  pre- 
servative. 

Impregnation  treatments  have  given  by  far  the  most  satis- 
factory results.  Three  processes  are  recommended,  the  Burnett, 
the  empty-cell  and  the  full-cell  creosote.  If  decay  is  not  un- 
usually severe  and  if  the  timbers  are  liable  to  be  broken  by  crush 
or  ''squeeze,"  the  Burnett  process  is  recommended.  Excellent 
results  can  be  secured  from  it.  If  the  timbers  are  set  in  mines 
where  there  is  much  moisture  and  where  decay  is  very  rapid, 
treatments  with  creosote  should  be  used,  the  empty-cell  method 
being  employed  for  porous  woods  containing  much  sapwood,  as 
loblolly  and  shortleaf  pines,  etc.,  and  the  full-cell  process  where 
the  timbers  are  refractory  and  the  percentage  of  sapwood  small, 
as  in  Douglas  fir,  hemlock,  and  hewed  timbers  generally.  One- 
half  pound  of  zinc  chloride  per  cubic  foot  is  sufficient  for  the  Bur- 
nett-treated timbers.  Six  to  12  pounds  per  cubic  foot  is  sufficiently 
heavy  for  the  creosoted  timbers.  All  these  timbers  ean  be  handled 
in  precisely  the  same  manner  as  in  treating  ties. 

The  practice  of  sawing  off  treated  mine  timbers  in  order  to 
make  them  fit  is  bad.  It  can  often  be  avoided  by  using  com- 
paratively short  timbers  and  wedging  them  into  place  by  means  of 
creosoted  wedges  or  caps.  In  this  manner  much  valuable  timber 
can  be  saved  and  decay  greatly  retarded. 

Square  Sets. — If  these  are  made  of  round  timbers  they  can  be 
handled  in  the  same  manner  as  props.  If  the  timbers  are  sawed 
or  hewn  and  are  not  susceptible  to  treatment,  the  full-cell  creosote 
treatment  is  recommended.  Care  should  be  taken  to  see  that 
the  ends  especially  are  well  protected,  and  if  for  any  reason 
it  is  necessary  to  retrim  these  timbers  after  they  have  been 
treated,  such  places  should  be  brushed  over  with  one  or  more 
coats  of  creosote. 


192        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Lagging. — It  seldom  pays  to  treat  lagging,  but  if  the  lagging  is 
made  of  sawed  lumber,  a  treatment  with  zinc  chloride  can 
profitably  be  given.  The  chief  advantage  in  treating  lagging 
rests  in  retarding  the  spread  of  the  wood-destroying  fungi. 

The  Treatment  of  Mine  Timbers  in  Relation  to  Fire. — This  is  a 
very  important  matter,  as  nothing  should  be  placed  in  the  mines 
which  will  increase  the  fire  hazard.  All  timbers  treated  with 
zinc  chloride  will  be  more  fire  resistant  than  untreated  timbers. 
Furthermore,  this  salt  tends  to  keep  the  timbers  moist,  and 
hence  under  pressure  they  will  act  more  like  green  timber,  viz., 
bend  considerably  before  they  break.  Much  importance  is 
attached  to  this  property  by  some  mine  operators,  as  it  gives  a 
warning  to  the  men  in  case  of  a  crush  or  fall  of  rock  or  earth. 

In  all  cases,  timbers  which  are  creosoted  should  first  be  air 
seasoned  for  at  least  1  month  before  they  are  placed  in  the 
mines.  This  will  enable  the  lighter  portions  of  the  oil  to 
evaporate  and  will  decrease  very  materially  the  ease  with  which 
the  timber  can  be  ignited.  After  it  has  once  air  seasoned, 
creosoted  timber  is  not  easily  ignited.  It  is  possible  to  hang  the 
naked  flame  of  a  miner's  torch  or  lamp  on  such  timber  without 
injury  other  than  a  charring  of  the  surface.  If;  however,  the 
timber  once  ignites,  it  will  burn  freely  and,  unfortunately,  emit 
dense  clouds  of  black  smoke.  Fire  in  creosoted  timber  is,  how- 
ever, easily  extinguished.  The  author  witnessed  the  effect  of  a 
fire  in  a  mine  shaft,  built  of  half  untreated  and  half  creosoted 
props,  where  the  flames  shot  from  the  mouth  of  the  shaft.  The 
fire  was  extinguished  by  smothering  the  shaft.  An  examination 
made  after  the  fire  showed  nearly  all  of  the  untreated  props 
destroyed,  while  those  creosoted  were  simply  charred  on  the 
surface  and  still  serviceable.  There  is  little  doubt,  however,  but 
what  zinc-treated  timbers  in  mines  are  preferable  to  creosoted 
timbers  when  judged  from  a  fire-hazard  standpoint.  They  are 
not  only  fire  resistant  in  themselves,  but  they  do  not  emit  odors 
which  may  be  objected  to  by  the  workmen  and  hence  cause 
anxiety  among  them.  For  further  information  on  the  inflam- 
mability of  timber  treated  with  zinc  chloride  and  creosote,  the 
reader  is  referred  to  Chapter  XVI. 

Cost  of  Treatments. — Table  30  gives  an  estimated  cost  of 
treating  mine  timbers.  It  is  assumed  that  creosote  costs  1  cent 
per  pound,  zinc  chloride  4  cents  per  pound,  peeling  and  seasoning 
about  1  cent  per  cubic  foot,  brush-treating  about  15  cents  per 


PLATE  XX 


FIG.  A. — Gangway  of  treated  mine  timbers,  Pottsville,  Pa.     (Forest  Service 

photo.) 


FIG.  B. — Rank  growth  of  fungus  on  mine  timbers. 

(Facing  page  192.) 


«  j.  c  vc  i  RLATE  XX 


FIG.  C. — Treated  and  untreated  mine  props.  Treated  prop  to  right  set 
at  same  time  as  failed  untreated  prop  at  left,  Pennsylvania.  (Forest 
Service  photo.) 


FIG.  D. — Untreated    mine    props    destroyed    by    decay    and    "squeeze/ 
Pennsylvania.     (Forest  Service  photo.) 


PROLONGING  THE  LIFE  OF  MINE  TIMBER 


193 


set,  and  impregnating  about  2  cents  per  cubic  foot.  A  sufficiently 
close  estimate  on  the  cost  of  treating  mine  ties  can  be  secured 
from  a  direct  comparison  with  cross-ties  already  given,  making 
allowance,  of  course,  for  tfee  differences  in  volume  between  the 
two. 

TABLE  30. — ESTIMATED  COST  OF  UNTREATED  AND  TREATED  PINE 
GANGWAY  SETS 

(One  set  consists  of  one  7-foot  collar,  one  9-foot  leg,  and  one  10-foot  leg;  average 
diameter  of  timber  about  13  inches) 


Method  of  treatment 

Amt.  of  pre- 
servative used 
per  set 

Cost  of 
preserva- 
tive 

Cost  of  peel- 
ing, seasoning 
treating 

Total 
cost  of 
set  in 
mine 

Unpeeled 

lb. 

$ 

$ 

$ 

8  50 

Peeled  and  seasoned  
Brush-treated  —  creosote  
Empty-cell  process 

28 
130 

0.28 
1  30 

0.26 
0.40 

0  80 

8.76 
9.18 
10  60 

Full-cell  process  (Bethell)  
Burnett  process  

312 
13 

3.12 
0.52 

0.80 
0.80 

12.42 

9.82 

In  western  United  States  the  cost  of  treating  mine  timbers  is 
high.     Some  figures  secured  from  practice  in  Montana  in  treating 
square  timbers  are  as  follows:1 
Cost  of  untreated  sets : 

1127  feet  B.M.  squared  timbers,  at  $20.50  per  M  B.M ).   $25.36 

Framing  timbers 13 . 50 

Cost  of  lagging,  at  $15  per  M  B.M 5.90 

Switching  and  unloading  charges 0 . 85 

Cost  of  placing  set 18 . 00 


Total  cost  of  untreated  set  in  place $63 . 61 

Cost  of  treatment: 

Cost  of  treating,  including  interest,  depreciation,  fuel,  and  labor 

charges 3 . 34 

Cost  of  creosote,  at  15.6  cents  per  gallon;  absorption  4.5  pounds 

per  cubic  foot 8 . 03 

Loading  and  unloading  charges 1 .23 

Total  cost  of  treatment 12 . 60 

Total  cost  of  treated  set  in  place 76.21 

Ecomony  of  Treatments. — Because  of  the  rapidity  with  which 
timber  placed  in  most  mines  decays,  the  economy  due  to  its 
treatment  is  very  striking.  As  stated  in  the  opening  of  this  chap- 

1  Bulletin  107,  United  States  Forest  Service. 
13 


194       THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


ter,  it  is  not  advisable  to  treat  all  of  the  timber  which  is  placed  in 
the  mine  because  much  of  it  is  intended  to  serve  only  a  short 
period.  But  for  permanent  shafts,  gangways  and  entries  it  will 
almost  invariably  be  found  that  a  treating  process  of  some  sort  is 
advisable  and  will  result  in  a  marked  economy.  Fortunately, 
some  reliable  records  on  the  life  of  treated  timber  in  mines  is 
available  on  which  fairly  accurate  estimates  of  economy  can  be 
based.  (See  Chapter  XX,  Reliable  Records  on  the  Life  of  Treated 
Timbers.)  Excluding  all  failures  from  crush  and  fire,  which  may 
be  nil  or  total,  the  economies  that  may  reasonably  be  expected 
when  such  woods  as  pine,  red  oak,  etc.,  are  used  are  shown  in 
Table  31. 

TABLE  31. — ESTIMATED  ANNUAL  CHARGES  OF  TREATED  AND.  UN  TREATED 

MINE  SETS 

(interest  5  percent  compounded  annually) 


Method  of  treatment 

Life  of 
timber 
(years) 

Cost  of 
timber  set 
in  mines 

Annual 
charges 

Untreated  
Brush-treated  —  creosote  . 

2 

5 

$8.50 
9  18 

$4.39 
2  12 

Burnett  process  

10 

9  82 

1  27 

Empty-cell  process 

11 

10  60 

1  27 

Full-cell  process  (Bethell)  

15 

12.42 

1.19 

V; 
"  ,          ' -Jk 

CHAPTER  XIII 

PROLONGING  THE  LIFE  OF  PAVING  BLOCKS 

Progress  of  Wood  Paving. — "The  first  use  of  wood  for  paving  is  said 
to  have  been  in  Russia,  where  crude  blocks  were  laid  several  centuries 
ago.  Wood  was  introduced  into  New  York  City  in  1835-36,  and  into 
London  in  1839.  Continental  Europe  was  slower  to  take  it  up. 

During  the  first  30  years  of  wood  paving  in  England  and  America 
the  chief  consideration  seems  to  have  been  the  form  of  block.  The  large 
and  unequal  interstices  between  the  round  blocks  then  commonly  used 
permitted  the  edges  to  wear  off  rapidly  into  a  corduroy  condition  which 
was  uncomfortable  to  the  traveler,  and  which  hindered  both  drainage  and 
cleaning,  thus  making  the  pavement  unsanitary  and  hastening  its  decay. 
To  remedy  this,  other  forms  of  block  were  devised,  many  of  which  were 
patented. 

In  the  United  States  perhaps  the  most  conspicuous  of  these  blocks  was 
the  'Nicholson/  patented  in  1848  and  laid  extensively  in  the  10  years 
following  the  civil  war.  The  block  was  rectangular,  which  gave  equal 
interstices;  but  this  by  no  means  solved  the  problem,  and  results  were 
no  better  than  before.  Little  thought  was  given  to  the  kind  of  wood 
used,  and  as  soft  a  wood  as  white  pine  was  frequently  laid.  The  blocks 
were  neither  seasoned  nor  treated  with  chemical  preservatives,  and 
quickly  decayed.  Wide  joints  permitted  water  to  get  under  the  pave- 
ment, where  it  was  absorbed  by  the  blocks,  with  the  result  that  they 
swelled,  so  that  the  pavement  often  heaved  from  its  foundation.  Fin- 
ally, the  foundation  was  usually  of  untreated  planks,  laid  directly  upon 
earth,  so  that  they  soon  decayed,  while  the  pavement  sank  into  ruts 
and  holes. 

Round  blocks,  mostly  of  cedar,  were  extensively  laid  in  the  Middle 
West.  They  made  neither  a  durable  pavement  nor  in  any  way  a  satis- 
factory one.  But  they  were  cheap  and  served  a  good  purpose  in  tiding 
fast-growing  cities  over  a  critical  period.  There  have  also  been  laid  in 
various  cities  pavements  of  oak,  cypress,  white  pine,  hemlock,  Washing- 
ton red  cedar,  cottonwood,  mesquite,  Osage  orange,  redwood,  Douglas 
fir,  and  tamarack.  In  nearly  all  these  cases  the  blocks  were  untreated, 
or  at  most  dipped  or  boiled  for  a  short  time  in  tar,  asphalt,  or  other  mix- 
ture of  supposed  preservative  value,  and  they  failed  to  give  satisfactory 
results.  Untreated  American  red  gum  was  tried  in  England,  and  for  a 
time  raised  great  hopes,  but  it  finally  proved  unsatisfactory. 

195 


196        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Some  species  of  eucalyptus,  especially  karri  (Eucalyptus  diversicolor) 
and  jarrah  (E.  marginata),  which  are  very  dense,  hard,  Australian  woods, 
have  been  laid  extensively  in  England.  In  London  these  woods  have 
shown  a  life  of  from  fifteen  to  twenty  years,  but  continued  use  has  not 
entirely  justified  the  hopes  first  entertained  for  them.  Their  structure  is 
too  dense  to  permit  impregnation  with  chemical  antiseptics,  without 
which  they  absorb  water  and  swell.  They  wear  much  more  slippery 
than  most  native  woods,  and  they  are  not  immune  from  decay,  though 
because  of  certain  antiseptic  gum-resins  which  they  contain  they  are 
more  so  than  any  untreated  native  woods.  In  England,  however,  they 
are  still  used.  Jarrah  blocks  were  laid  on  Twentieth  Street,  New  York 
City,  in  1895,  but  were  removed  in  1904.  The  cost  of  this  pavement  was 
about  $5  per  square  yard,  which  would  exclude  these  woods  from  exten- 
sive use  in  America  even  should  they  make  a  better  pavement  than  our 
best  creosoted  native  woods,  which  is  not  likely."1 

The  failure  of  the  untreated  woods  turned  attention  to  blocks 
artificially  preserved.  One  of  the  earliest  records  in  our  country 
is  in  the  city  of  Galveston,  Texas,  which  laid  some  creosoted  pine 
blocks  in  1873.  These  blocks  gave  satisfactory  service  for  30 
years,  when  they  were  destroyed  by  a  flood.  Little  progress  was 
made  in  advancing  the  use  of  wood  blocks  until  within  the  past 
10  years,  when  the  demand  for  a  high-class  pavement,  especially 
in  large  cities,  caused  a  big  increase  in  the  number  laid.  This 
growth  is  shown  by  the  following  table : 

TABLE  32. — AMOUNT  OF  WOOD  USED  ANNUALLY  IN  THE  UNITED  STATES 
FOR  PAVING  BLOCKS 


Year 

Amount  of  wood  used  —  cubic  feeta 

1907  

1908  

2,874,560 
1,260,020 

1909                    

2,994,290 

1910 

4,692,453 

1911  
1912  

10,145,724 
7,397,095 

0  =  divide  figures  given  by  2.625  to  convert  into  square  yards. 

Mr.  George  W.  Tillson,  Chief  Engineer,  Bureau  of  Highways 
of  New  York  City,  conducted  an  inquiry  on  the  comparative 
value  of  various  forms  of  pavements  in  which  the  opinions  of 
several  city  engineers  were  asked  in  regard  to  the  salient  points 
to  be  considered  in  judging  a  street  pavement.  Mr.  Tillson 
summarized  these  opinions  in  his  book  entitled  "Street  Paving 

1  Extract  Circular  141,  United  States  Forest  Service. 


PROLONGING  THE  LIFE  OF  PAVING  BLOCKS 


197 


and  Paving  Materials."     The  results  of  this  investigation  are 
given  in  Table  33. 

TABLE  33. — COMPARATIVE,  VALUE  OF  DIFFERENT  PAVEMENTS 


Pavement  qualities 

Per- 
cent- 
age 

Gran- 
ite 

Sand- 
stone 

As- 
phalt 
(sheet) 

As- 
phalt 
(block) 

Brick 

Mac- 
adam 

Creo- 
soted 
wood 

Cheapness  (first  cost)  .  . 
Durability  

14 
20 

4.0 
20.0 

4.0 
17.5 

6.5 
10.0 

6.5 
14.0 

7.0 
12.5 

14.0 
6.0 

4.5 
14.0 

Ease  of  maintenance.  .  . 
Ease  of  cleaning  
Low  traction  resistance. 
Freedom  from  slipperi- 
ness  (average  of  con- 
ditions)   
Favorableness  to  travel 
Acceptability  

10 
14 
14 

7 
4 
4 

9.5 
10.0 

8.5 

5.5 
2.5 
2.0 

10.0 
11.0 

9.5 

7.0 
3.5 
2.5 

7.5 
14.0 
14.0 

3.5 
4.0 
3.5 

8.0 
14.0 
13.5 

4.5 
3.5 
3.5 

8.5 
12.5 
12.5 

5.5 
3.0 
2.5 

4.5 
6.0 
8.0 

6.5 
3.0 
2.5 

9.5 
14.0 
14.0 

4.0 
3.5 
4.0 

Sanitary  quality  

13 

9.0 

8.5 

13.0 

12.0 

10.5 

4.5 

12.5 

Total  number  of  points 

100 

71.0 

73.5 

76.0 

79.5 

74.5 

55.0 

80.0 

Average  cost  per  square 
yard,  laid,  1905  

$3.26 

$3.50 

$2.36 

$2.29 

$2.06 

$0.99 

$3.10 

Favorableness  to  travel  is  dependent  chiefly  upon  smoothness  and  freedom  from  dust  and 
mud,  secondarily  upon  the  qualities  composing  "Acceptability." 

Acceptability  includes  noise,  reflection  of  light,  radiation  of  heat,  emission  of  unpleasant 
odors,  etc.  It  chiefly  concerns  the  pedestrian  and  the  adjoining  resident. 

Cost  per  square  yard  includes  concrete,  but  not  excavation,  curbing,  etc.;  except  for 
macadam,  which  is  not  usually  laid  on  concrete. 

Other  investigators  have  attempted  similar  comparative 
studies,  and  while  no  two  of  them  agree  in  all  respects,  a  high 
rating  is  given  to  wood-block  pavement  in  regard  to  its  noise- 
lessness,  durability,  and  sanitation. 

On  the  other  hand,  the  pavement  has  been  severely  criticized 
on  account  of  its  high  initial  cost  and  troubles  experienced  with 
slipperiness,  expansion  or  buckling,  and  the  exudation  of  oil,  or 
"  bleeding."  From  investigations  which  have  been  conducted, 
it  is  believed  that  much  progress  has  been  made  in  overcoming 
some  of  these  objections  and  that  before  long  all  of  them,  except 
perhaps  high  initial  cost,  will  be  eliminated. 

Selection  of  Species. — At  present  most  of  the  wood  blocks  used 
(over  three-fourths  of  the  total  number)  are  cut  from  the  "  south- 
ern yellow  pine."  This  is  rather  indefinite  as  regards  the  exact 
species,  as  the  term  may  include  the  longleaf,  shortleaf,  Cuban, 
or  even  loblolly  pines.  What  is  wanted,  undoubtedly,  is  the 
longleaf  pine,  but  according  to  present  practice  there  is  no 
certain  way  of  telling  these  various  pines  apart  except  by  a  most 
careful  microscopic  examination,  which  in  commerical  work  is, 


198        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

of  course,  impracticable.  Specifying  a  certain  number  of  rings 
per  inch  is  of  assistance  but  is  by  no  means  certain.  As  the 
strength  of  wood  is  directly  proportional  to  its  dry  weight,  it  is 
believed  that  a  specification  coupling  rings  per  inch  with  dry 
weight  would  give  the  engineer  more  definitely  what  he  desires. 
Branding  lumber  at  its  point  of  production  would  also  be  of 
assistance  to  the  inspector. 

In  addition  to  the  "southern  yellow  pine,"  blocks  made  of 
Douglas  fir,  red  gum,  tamarack,  larch,  and  Norway  pine  are  also 
used,  although  in  comparatively  small  amounts. 

The  intrinsic  properties  demanded  of  a  good  block  wood  are 
resistance  to  wear,  uniformity  in  structure  and  freedom  from 
defects,  adaptability  to  treatment,  and  ability  to  hold  its  shape 
after  treatment.  These  requirements  coupled  with  a  reasonably 
low  cost  limit  very  materially  the  number  of  woods  which  can  be 
used.  In  addition  to  the  woods  already  mentioned,  it  is  believed 
the  following  are  worthy  of  trial :  Beech,  birch,  black  gum,  maple 
sycamore,  tupelo,  hemlock,  lodgepole  and  western  yellow  pines. 
They  will,  of  course,  have  to  be  handled  somewhat  different 
from  standard  practice,  but  some  of  them  possess  desirable 
qualities  for  street  pavements. 

Blocks  which  are  cut  from  a  very  hard  wood  have  a  tendency 
to  wear  smooth,  so  that  unless  the  pavement  is  sanded  periodically 
they  may  prove  too  slippery  for  satisfactory  use.  If  some  of  the 
woods  above  suggested  give  good  service  in  pavements,  it  should 
tend  in  certain  cases  to  lower  the  initial  cost  of  wood-block 
pavements. 

The  Manufacture  of  Paving  Blocks. — Paving  blocks  are  usually 
cut  from  planks  of  varying  lengths,  about  3  1/2  to  4  inches  thick, 
and  6  to  10  inches  wide.  These  are  fed  into  the  paving-block 
machine,  which  is  fitted  with  a  series  of  saws  so  spaced  as  to  cut 
the  blocks  to  exact  depth.  In  this  manner  many  blocks  are  cut 
at  one  time.  The  capacity  of  the  machine  varies  but  good 
machines  can  turn  out  200  square  yards  of  4-inch  blocks  per 
hour.  On  leaving  the  block  machine,  the  blocks  fall  onto  a 
conveyor,  where  they  are  inspected  and  all  imperfect  ones 
removed.  The  rest  are  carried  mechanically  to  the  treating  cylin- 
der or  cylinder  cars  and  dumped  automatically.  It  is  very 
important  that  the  blocks  be  cut  to  an  exact  depth,  for  if  this  is 
not  done  the  surface  of  the  pavement  will  be  uneven  and  its  wear 
greatly  augmented.  The  prevailing  depth  of  blocks  for  street 


PROLONGING  THE  LIFE  OF  PAVING  BLOCKS  199 

work  varies  from  3  to  4  inches,  the  smaller  being  used  for  light 
and  the  larger  for  heavy  traffic.  In  Europe  the  practice  is 
to  use  deeper  blocks  than  in  our  country.  This,  of  course,  greatly 
increases  the  cost  of  the  payment  but  is  claimed  to  give  longer 
life  and  greater  resilience.  It  is  believed  that  the  question  of 
proper  depth  of  the  block  is  not  given  the  attention  to  which  it  is 
entitled.  As  all  woods  vary  in  strength,  it  is  only  reasonable  to 
cut  them  to  different  depths  depending  upon  their  strength. 
Blocks  are  laid  with  the  grain  vertical.  This  subjects  them  to 
shear  parallel  to  the  grain,  which  is  the  weakest  direction  in  which 
a  load  can  be  applied.  Failure  from  shear  is  therefore  great,  and 
many  blocks  have  been  shattered  in  practice  because  of  such 
failure.  It  is  believed,  therefore,  that  if  best  service  is  to  be 
secured,  blocks  low  in  shear  should  be  cut  to  greater  depths  than 
blocks  which  are  high. 

The  planks  from  which  the  blocks  are  cut  are  generally  air 
seasoned.  It  is  believed  unnecessary  to  do  this,  in  fact  some- 
times inadvisable.  If  cut  from  green  planks,  the  blocks  will  be 
treated  at  their  maximum  size,  so  that  danger  from  expansion 
after  they  are  placed  in  a  street  will  be  lessened.  Most  woods 
treat  easiest  in  the  direction  of  the  grain,  so  that  the  problem  of 
securing  a  good  penetration  in  blocks  only  a  few  inches  in  length 
is  not  a  difficult  one. 

Specifications  for  paving  blocks  vary  considerably.  The  fol- 
lowing is  a  fair  sample  of  what  is  generally  required :  The  blocks 
shall  be  made  of  prime,  sound  timber,  and  no  wood  averaging 
less  than  6  rings  to  the  inch,  measured  radially  from  the  center  of 
the  heart  shall  be  used  or  wood  that  is  poorly  manufactured  and 
contains  loose  knots,  worm  holes,  and  other  defects.  The  blocks 
shall  be  from  5  to  10  inches  long,  3  to  4  inches  in  depth  parallel  to 
the  grain  depending  upon  traffic,  and  3  to  4  inches  in  width,  pro- 
vided all  blocks  furnished  for  one  street  are  of  uniform  width  and 
depth.  A  variation  of  1/16. inch  in  depth  and  1/8  inch  in  width 
will  be  allowed. 

Methods  of  Treatment. — Nearly  all  of  the  paving  blocks 
treated  in  the  United  States  are  impregnated  with  coal-tar 
creosote,  either  alone  or  in  mixture  with  tar,  by  the  full-cell 
method.  In  a  few  cases,  the  blocks  are  simply  dipped  in  oil 
(creosote  or  carbolineum)  and  lately  the  zinc-creosote  process 
has  been  advocated  for  blocks  used  in  factories  and  shops.  A 
common  method  consists  in  placing  the  air-seasoned  blocks  in  a 


200        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

treating  cylinder  (and  sometimes  drawing  a  vacuum),  after  which 
the  oil  is  admitted  and  forced  into  them  under  a  pressure  of  about 
150  pounds  per  square  inch  until  the  desired  amount  is  absorbe/L 
The  cylinder  is  then  drained  of  excess  oil  and  a  vacuum  drawn  for 
about  1/2  hour  to  dry  the  blocks,  after  which  they  are  removed 
and  are  ready  for  use.  This  practice  is  modified  by  certain  opera- 
tors, who  steam  the  blocks  aftei  they  are  run  into  the  cylinder 
and  then  pull  a  vacuum  after  the  steaming  period.  A  few  opera- 
tors also  steam  the  blocks  after  they  have  been  impregnated  with 
the  oil. 

The  amount  and  kind  of  oil  inj  ected  varies  considerably.  Nearly 
all  specifications  call  for  a  heavy  grade,  viz.,  one  with  a  specific 
gravity  of  at  least  1.08  at  25°  C.  and  in  some  cases  as  high  as  1.12. 
Many  engineers  allow  the  oil  to  be  mixed  with  certain  amounts  of 
"  filtered  tar"  in  order  to  bring  up  its  gravity.  Some  also  allow 
water-gas-tar  creosote  to  be  mixed  with  the  coal-tar  creosote.  The 
amount  of  oil  required  is  generally  16  pounds  per  cubic  foot,  al- 
though this  varies  from  12  to  20.  It  can  thus  be  seen  that  the 
practice  in  treating  blocks  is  by  no  means  a  uniform  one,  but  dif- 
fers with  the  opinions  of  the  various  engineers. 

The  Chicago  Creosoting  Company  has  recently  constructed  a 
block  plant  wherein  the  cylinders  are  placed  vertically.  (See 
Plate  XI,  Fig.  D.)  The  blocks  are  dumped  into  the  top  of  the 
cylinders  by  a  mechanical  conveyor.  After  the  desired  absorp- 
tion has  been  obtained,  the  excess  oil  is  drained  from  the  cylin- 
ders, and  a  door  in  the  bottom  of  the  cylinder  is  opened  allowing 
the  blocks  to  fall  directly  into  cars  ready  for  shipment.  This 
method  does  away  with  cylinder  cars  entirely  and  is  claimed  to 
cut  down  the  cost  of  handling. 

Troubles  Experienced  with  Wood-block  Paving. — It  has  al- 
ready been  stated  that  wood-block  paving  at  times  has  serious 
objections.  Unfortunately,  the  exact  cause  of  these  difficulties 
is  not  known  at  present,  so  that  definite  remedies  for  all  conditions 
cannot  be  prescribed.  Opinions  and  practice  differ  widely.  The 
chief  objections  are  slipperiness,  exudation  of  oil,  and  expansion  of 
the  blocks. 

Slipperiness. — In  general,  the  harder  the  blocks  the  smoother 
the  pavement  becomes.  Blocks  of  softer  wood  give,  therefore, 
less  trouble  from  slipperiness,  but  there  is  a  limit  to  which  the 
softness  can  go,  as  blocks  which  are  too  soft  will  of  course  wear 
rapidly. 


PROLONGING  THE  LIFE  OF  PAVING  BLOCKS  201 

Oil  and  tar  on  the  surface  of  the  pavement  also  increases 
slipperiness.  It  is  believed  that  this  cause  can  be  largely  over- 
come as  will  be  discussed  below. 

If  our  streets  were  sanded-from  time  to  time,  as  is  done  abroad, 
the  surface  of  the  Blocks  would  become  roughened  because  the 
sand  would  embed  itself  in  the  wood.  This  should  be  done 
particularly  in  cold  weather,  when  ice  forms  on  the  pavement. 
Asphalt  is  also  subject  to  the  same  objection  in  cold  weather  and  a 
similar  treatment  should  be  given  it. 

Exudation  of  Oil. — This  is  about  the  most  troublesome  objection 
raised  against  wood  blocks.  The  oil  and  tar  may  at  times  exude 
to  the  surface  and  form  a  thick,  disagreeable  mat,  which  sticks 
to  the  feet  of  pedestrians  and  is  generally  objectionable.  In 
certain  cities  like  Chicago,  the  trouble  became  so  acute  as  to 
arouse  bodies  of  citizens  into  a  protest  against  what  was  termed 
the  "  black  plague."  Other  cities  like  Minneapolis  have  for- 
tunately been  free  from  these  troubles.  It  is  probable  that  the 
exudation  of  oil,  commonly  called  " bleeding"  or  " weeping," 
is  due  to  several  causes,  such  as  too  heavy  an  impregnation,  too 
much  pitch  or  tar  poured  into  the  joints,  too  rapid-grown  blocks, 
improper  treatment,  and  too  close  laying  of  the  blocks.  From 
observations  and  tests  made  by  the  author  it  is  believed  that 
bleeding  can  be  eliminated  if  (1)  only  slow-grown  wood  is  used 
for  the  blocks;  (2)  if  green  timber  or  steamed  seasoned  timber 
is  used;  (3)  if  a  strong  preliminary  and  final  vacuum  is  drawn 
before  and  after  the  oil  is  injected;  (4)  if  when  tar  is  used  the 
blocks  are  steamed  slightly  after  the  oil  is  injected;  (5)  if  the 
penetrations  are  made  complete;  (6)  if  impregnations  no  greater 
than  16  pounds  per  cubic  foot  are  given;  (7)  if  straight  coal-tar 
creosote  or  coal-tar  creosote  containing  only  small  amounts  of 
carbon-free  tar  is  injected;  (8)  if  the  blocks  are  not  laid  too  close 
together;  (9)  if  excess  tar  or  pitch  is  not  poured  between  the 
joints.  All  of  these  requirements  can  be  easily  met  without  added 
cost. 

Expansion  of  the  Blocks. — This  is  commonly  called  "  mush- 
rooming," "buckling,"  or  "pop  ups."  (See  Plate  XXI,  Fig.  A.) 
The  true  cause  of  it  is  not  known  except,  of  course,  that  the 
blocks  are  under  heavy  pressure.  If  the  blocks  are  laid  very 
dry  and  close  together  there  will  be  little  room  for  expansion  and 
the  pavement  will  be  very  liable  to  buckle.  It  is  believed  that 
if  the  blocks  are  well  penetrated  so  that  their  tendency  to  absorb 


202       THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

moisture  will  be  decreased,  are  treated  green  or  steam  seasoned, 
are  laid  fairly  loose  and  have  proper  expansion/joints,  little  or 
no  trouble  from  buckling  will  be  experienced. 

It  is  wasted  effort  to  try  and  make  the  blocks  nonexpansive, 
for  no  matter  how  much  oil  is  forced  into  them  they  will  absorb 
more  or  less  water  in  time.  Furthermore,  the  oil  and  wood  will 
expand  due  to  rise  in  temperature.  Best  practice,  therefore,  is  to 
keep  the  absorption  of  water  to  a  minimum  by  proper  treatment 
and  to  allow  for  expansion  by  carefully  laying  the  pavement  as 
described  above. 

.Method  of  Laying  Wood  Blocks. — In  street  work,  a  concrete 
base  about  4  to  8  inches  thick  is  first  constructed,  this  having  the 
desired  crown.  Over  this  is  then  placed  a  layer  of  coarse  sand 
about  1  inch  thick.  The  blocks  are  then  laid  on  this  smoothed 
sand  cushion,  after  thich  they  are  tamped  and  rolled  into  final 
position.  Asphalt,  grout,  or  hot  pitch  is  then  poured  into  the 
joints  and  further  worked  into  them  with  a  squeegee.  The 
surface  is  then  covered  with  sand  and  the  pavement  is  ready  for 
use.  In  a  few  days  the  excess  sand  is  removed  from  the  pavement. 

Experiments  have  been  tried  in  doing  away  with  the  sand 
cushion  by  pouring  hot  pitch  directly  over  the  concrete  base  and 
embedding  the  blocks  in  it.  These  pavements  have  not  been  in 
service  sufficiently  long  to  judge  of  the  results. 

The  angle  at  which  the  blocks  are  laid  has  also  been  tested. 
It  is  found  that  blocks  laid  at  an  angle  of  671/2°  with  the  curb 
show  least  wear,  those  at  45°  next,  and  those  at  90°  most. 

The  character  of  filler  to  be  used  is  still  an  open  problem. 
Coal-tar  pitch  and  asphalt  seem  to  be  preferred.  The  former  is 
objectionable  in  that,  if  not  properly  applied,  it  will  ooze  to  the 
surface.  Asphalt  is  free  from  this  objection  but  is  more  difficult 
to  work  into  the  joints. 

Expansion  joints  are,  at  times,  laid  not  only  along  the  curb 
(about  1  inch  in  width  on  a  50-foot  roadway)  but  crosswise. 

In  some  cities  strips  of  wood  about  1/4  inch  thick  are 
placed  between  the  blocks,  thus  leaving  joints  for  a  better  footing 
of  horses.  This  practice,  however,  is  not  common. 

When  wood  blocks  are  used  on  certain  types  of  bridges,  they 
are  laid  directly  upon  creosoted  plank.  This  adds  considerably 
to  the  lightness  of  the  bridge  and  is  considered  a  distinct 
advantage  over  other  forms  of  pavement. 

Cost  of  Treatment. — The  cost  of  treating  wood  paving  blocks 


PLATE  XXI 


FIG.  A. — A  "popup,"  or  failure  in  a  street  laid  with  creosoted  blocks  due 

to  their  expansion. 


FIG.  B. — Wood  block  pavements — grading  the  sand  cushion  and  laying  the 
blocks,  Minneapolis,  Minn.     (Forest  Service  photo.) 

(Facing  page  202.) 


PLATE  XXI 


—-'-•••  -  •  •     '• •     ...   — -. — - — -  -  —   - j 

FIG.  C. — Working  the  tar  filler  into  the  joints  of  a  newly  laid  wood  block 
pavement.     (Forest  Service  photo.) 


FIG.  D. — Pine  beams  in  a  building  completely  rotted  in  the  end  after  *30 
years'  service,  Madison,  Wis. 


PROLONGING  THE  LIFE  OF  PAVING  BLOCKS  203 

varies  with  the  kind  of  oil  specified,  the  amount  to  be  injected,  the 
kind  and  size  of  the  block,  and  other  peculiarities  in  the  specifica- 
tions. If  ordinary  creosote  is  used  it  can  be  obtained  for  about 
8  cents  per  gallon.,  GenerdRy,  however,  a  higher  grade  is  re- 
quired, which  in  some  cases  costs  12  to  15  cents  or  more  per 
gallon.  Assuming  the  cost  of  the  oil  to  be  1  cent  per  pound 
and  16  pounds  to  be  injected  per  cubic  foot,  the  cost  of  treating  a 
square  yard  of  3  1/2-inch  blocks  will  be  about  45  to  50  cents,  and 
of  4-inch  blocks  about  52  to  57  cents.  This,  of  course,  is  but  a 
fraction  of  the  total  cost  of  the  pavement,  which,  in  general, 
varies  from  about  $2.20  to  $3.70  per  square  yard,  making  it  one 
of  the  most  expensive  pavements  in  use. 

Advantages  of  Wood-block  Paving. — Wood-block  pavements 
possess  some  very  desirable  properties,  the  chief  ones  being 
sanitation,  durability,  ease  of  repair,  low  traffic  resistance,  ease  of 
cleaning,  and  absence  of  noise.  Friends  of  the  pavement  will 
find  many  other  points  to  extoll,  but  the  above  list  may  be 
considered  conservative. 

Coal-tar  creosote  is  a  strong  antiseptic,  and  as  large  quantities 
of  it  are  forced  into  the  blocks,  its  presence  alone  tends  to  keep 
the  street  in  a  healthy,  sanitary  condition. 

The  durability  of  wood  blocks  when  properly  laid  is  surprising. 
Data  collected  on  a  test  pavement  in  Minneapolis,  where  ac- 
curate traffic  records  are  kept  over  one  of  the  busiest  streets  in 
the  city,  show  a  wear  of  about  1/32  inch  per  year.  The  expe- 
riences of  several  cities  have  shown  the  marked  value  of  wood 
blocks  in  comparison  with  the  durability  of  other  kinds  of 
pavement.  There  is  no  doubt  but  what  the  good  results  already 
obtained  could  be  considerably  bettered  if  American  munici- 
palities only  took  better  care  of  their  pavements.  In  this  respect 
Europe  is  far  ahead  of  us. 

The  ease  with  which  wood-block  pavements  can  be  repaired 
is  all  the  more  reason  why  better  care  should  be  taken  of  them. 
If  a  depression  once  starts  it  will  grow  rapidly  until  a  considerable 
hollow  is  formed.  The  time  to  repair  such  failures  is  in  their 
beginning  when  all  that  is  necessary  is  to  remove  a  few  blocks, 
smooth  the  sand  cushion,  and  add  new  ones. 

The  depressions  caused  by  vehicles  and  horses  in  asphalt  on 
hot  days  is  well  known.  This,  of  course,  means  the  load  is 
harder  to  pull.  Wood  blocks  do  not  have  this  objection  and 
because  of  their  smooth  surface  make  traffic  run  smooth. 


204       THE  PRESERVATOIN  OF  STRUCTURAL  TIMBER 

The  even  surface  of  wood-block  pavements  enables  them  to 
be  easily  cleaned  and,  of  course,  adds  to  their  santitation. 

It  is  perhaps  the  noiselessness  of  wood  blocks  which  makes 
them  so  desirable,  especially  in  congested  business  districts, 
and  has  earned  for  them  the  title  of  the  " silent  pavement." 
This  quality  has  placed  wood-block  pavements  in  high  regard 
and  is  largely  responsible  for  their  rapid  growth  in  our  large 
cities. 

In  all  of  the  above,  it  has  been  assumed  that  the  pavements 
were  properly  laid,  for  if  this  is  not  done  poor  results  are  bound  to 
follow.  There  is  no  unusual  difficulty  in  properly  laying  a  wood- 
block pavement. 

Wood  Blocks  for  Barns,  Factories,  Etc. — Considerable  progress 
has  been  made  within  the  past  few  years  in  introducing  wood- 
block flooring  in  factories,  car  barns,  ferry  ships,  etc.,  where  it 
has  given  good  service.  It  is  liked  by  the  workmen  in  preference 
to  cement  floors  because  of  its  "touch."  It  is  durable,  easily 
repaired,  sanitary,  and  dustless.  For  use  under  such  conditions 
the  blocks  are  often  cut  smaller  and  treated  with  less  oil  than 
blocks  intended  for  streets.  In  fact,  the  Rueping  and  Card 
processes  are  sometimes  employed,  thus  decreasing  perceptibly 
the  cost  of  treating  the  blocks.  The  blocks  are  laid  in  much  the 
same  manner  as  for  street  work  except  that  the  angle  of  the 
courses  is  almost  invariably  90°. 


CHAPTER  XIV 
PROLONGING  THE  LIFE  OF  SHINGLES 

Shingles  are  subject  to  common  forms  of  destruction,  (1) 
decay  and  (2)  fire.  If  made  from  durable  woods,  the  problem 
of  protection  from  decay  is  not  serious,  as  shingle  roofs  may 
easily  last  25  years  or  more.  Protection  from  fire  is  of  greater 
importance,  especially  where  the  houses  are  close  together.  In 
congested  districts  the  use  of  shingles  is  now  almost  entirely 
obsolete.  However,  shingle  roofs  possess  certain  desirable 
properties  so  that  their  use  in  dwellings  will  undoubtedly  continue 
to  be  extensive. 

Selection  of  Species. — In  round  numbers  about  15  billion 
shingles  are  used  annually  in  the  United  States,  about  75  per- 
cent of  which  are  of  cedar — mostly  the  western  red  cedar  of 
Washington.  Next  in  rank  come  cypress  and  yellow  pine,  each 
furnishing  about  9  percent.  Then  redwood  with  3  percent,  white 
pine  2  percent,  and  spruce  1  percent.  The  other  species  such  as 
chestnut,  hemlock,  western  pine,  and  oak  all  furnish  less  than 
1  percent.  With  the  exception  of  oak  and  chestnut,  the  total 
cut  of  which  is  insignificant,  it  will  be  noticed  that  all  of  the 
shingles  are  made  from  coniferous  woods. 

The  ideal  shingle  is  one  which  is  light  in  weight,  durable,  and 
will  "lay  flat"  without  checking,  warping,  or  splitting.  Western 
red  cedar  admirably  meets  these  requirements.  Excellent  service 
is  also  secured  from  cypress  and  redwood  shingles,  both  of  which 
possess  remarkable  durability. 

The  best  grades  of  shingles  are  cut  only  from  clear  timber  free 
from  all  defects.  Sapwood  is  also  excluded,  since  it  is  not  very 
decay  resistant.  If,  however,  the  shingles  are  given  a  thorough 
preservative  treatment,  sapwood  should  not  be  considered  a 
defect,  and  in  some  cases  treated  sapwood  shingles  can  be  obtained 
at  no  greater  cost  than  untreated  shingles  of  all  heartwood. 

METHODS  OF  TREATING  SHINGLES 

Treating  against  Decay. — The  most  common  method  of  pro- 
tecting shingles  from  decay  is  to  dip  them  in  a  preservative  and 

205 


206        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

after  they  have  dried  nail  them  on  the  roof.  There  are  several 
preservatives  sold  on  the  market  for  this  purpose  under  the  name 
of  "  shingle  stain/'  which  not  only  preserve  the  shingle  but  color  it. 
For  best  results,  the  shingles  should  be  thoroughly  air  dry  when 
they  are  dipped  and  the  preservative  should  be  warm  or  even 
hot.  As  a  general  rule,  only  that  portion  of  the  shingle  which  is 
exposed  is  dipped,  the  upper  or  thinner  portion  being  in  this 
manner  covered  by  the  treated  portion  of  the  shingle  next  above 
it  on  the  roof.  Roofs  laid  in  this  manner  are  frequently  given  a 
final  coating  of  preservative  after  they  are  laid,  in  order  to  insure 
a  uniform  color  and  the  treatment  of  all  exposed  portions. 

Cheaper  and  less  efficient  results  are  obtained  if  the  shingles 
are  simply  brush-treated  with  the  preservative  after  they  are  laid. 
It  is  doubtful  if  ordinary  paint  preserves  the  life  of  shingles;  in 
fact,  it  may  hasten  their  decay.  Paint  is  of  value,  however,  in 
certain  cases;  in  that  it  tends  to  make  the  shingles  lie  flat  and 
hence  prevent  leaks. 

Most  efficient  results  in  treating  shingles  against  decay  con- 
sists in  impregnating  them  with  the  preservative.  This  is 
done  either  in  open  tanks  or  pressure  plants.  The  absorption 
of  the  preservative  should  not  be  so  great  as  to  unnecessarily 
increase  the  cost  of  the  shingles  or  cause  them  to  ooze  and 
drip  oil  on  hot  days.  An  absorption  of  10  pounds  per  bundle 
is  ample.  In  either  of  these  processes  the  shingles  can  be 
treated  in  the  bundle,  provided  they  are  not  strapped  too  tight 
together.  If  the  open-tank  process  is  used  the  shingles  should 
be  removed  while  hot;  if  the  pressure  process  is  used,  a  final 
vacuum  should  be  drawn.  These  manipulations  are  advisable  in 
order  to  dry  the  shingles.  If  treated  in  this  manner  sap  shingles 
can  be  made  as  resistant  to  decay  as  heart  shingles,  and  inferior 
shingle  woods  like  hemlock  and  yellow  pine  made  exceedingly 
durable. 

Shingles  treated  with  creosote  or  the  so-called  shingle-stains 
have  a  very  strong  odor  which  to  many  people  is  objectionable. 
This  odor,  however,  decreases  with  age  and  in  time  ceases  en- 
tirely. Furthermore,  the  rain-water  off  a  freshly  treated  roof  is 
very  liable  to  smell  and  taste  of  the  preservative  at  least  until  the 
roof  has  been  exposed  for  several  weeks. 

Treating  against  Fire. — Practically  nothing  has  been  done  to 
date  in  treating  shingles  against  fire.  The  recent  agitation  against 
shingle  roofs  in  certain  cities,  has,  however,  caused  considerable 


PROLONGING  THE  LIFE  OF  SHINGLES  207 

interest  in  this  matter  and  several  concerns  are  now  at  work 
attempting  to  render  shingles  noncombustible.  Ordinary  fire- 
proofing  compounds  like  ammonium  chloride,  ammonium  phos- 
phate, etc.,  are  obj  ectionablftdn  that  they  are  soluble  in  water  and 
consequently  will  soon  be  washed  from  the  wood.  It  is  possible, 
however,  that  their  use  might  be  rendered  practicable  by  paint- 
ing the  shingles  treated  in  this  manner  with  a  waterproof  paint 
after  they  have  been  laid.  A  large  variety  of  experiments  are 
now  under  way,  some  of  which  indicate  hope  of  a  satisfactory 
solution  of  the  problem,  but  at  this  writing  no  method  that 
can  be  called  successful  is  known.  Greatest  danger  from  fire 
is  caused  by  the  shingles  curling  and  igniting  from  sparks  or 
brands.  If  the  shingles  are  made  to  lie  flat  their  liability  to 
catch  on  fire  from  such  sources  is  greatly  decreased.  Some  of  the 
so-called  "  fireproof "  paints  now  on  the  market  are  of  value  in 
this  respect  and  tests  known  to  the  author  have  indicated  that 
even  ordinary  paint  will  be  found  of  material  assistance. 

Cost  of  Treating  Shingles. — If  shingles  are  impregnated  with 
creosote,  the  cost  will  be  about  $1.25  to  $1.75  per  thousand.  If 
they  are  simply  dipped  into  the  creosote  the  cost  will  be  about 
$0.60  to  $1.50  per  thousand;  if  brush -treated  with  two  coats  after 
the  roof  is  laid,  about  $0.40  to  $0.90  per  100  square  feet.  Shingle 
stains  which  cost  from  about  $0.40  to  $1  per  gallon  make,  of 
course,  a  more  expensive  treatment,  the  cost  of  dipping  per  thous- 
and being  about  $1.50  to  $3.50,  and  for  simply  brush-treating  after 
the  roof  is  laid  about  $0.60  to  $1.50  per  100  square  feet. 


CHAPTER  XV 
PROLONGING  THE  LIFE  OF  LUMBER  AND  LOGS 

Methods  of  Treating  Lumber  for  Rough  Construction. — An 
immense  quantity  of  structural  timber  is  used  annually  in  the 
United  States  under  conditions  which  subject  it  to  decay.  Un- 
fortunately, only  a  small  percentage  is  treated,  so  that  our 
depreciation  losses  are  both  rapid  and  large.  Of  course,  wherever 
the  timber  can  be  protected  from  the  weather,  or  warm  damp  at- 
mosphere, no  artificial  treatment  is  necessary,  as  it  willu  nder  such 
conditions  last  indefinitely.  However,  in  bridges,  trestles,  piers, 
walks,  platforms,  docks,  etc.,  etc.,  where  such  timbers  are  used, 
failure  from  decay  is  all  too  common.  (See  Plate  XXI,  Fig.  D.) 
This  is  particularly  true. if  the  wood  comes  in  contact  with  the 
soil.  While  it  is  not  possible  to  lay  down  a  set  of  instructions 
which  will  cover  all  cases,  certain  general  rules  should,  however, 
prove  of  direct  value  to  those  using  this  class  of  material. 

Whenever  possible,  all  such  timbers  shonld  be  kept  from 
contact  with  the  ground.  In  many  cases,  they  can  be  placed 
on  concrete  or  stone  piers,  and  by  this  simple  treatment,  their 
life  considerably  prolonged. 

The  most  effective  treatment  which  can  be  given  such  timbers 
is  to  impregnate  them  with  coal-tar  creosote.  For  severe  cases, 
the  full-cell  process  should  be  used;  for  less  severe,  the  empty- 
cell  or  Card.  From  5  to  12  pounds  of  oil  should  be  injected, 
depending  upon  local  conditions.  As  sap  wood  is  just  as  strong  as 
heartwood,  the  treatment  of  this  kind  often  enables  the  use  of 
sappy  timbers,  which,  untreated,  would  not  be  used.  Hence, 
specifications  for  the  raw  material  can  be  made  more  lenient  and 
the  timber  can  frequently  be  secured  at  a  lower  initial  price.  All 
structural  timbers  injected  with  preservatives  should  be  framed  as 
close  to  final  dimensions  before  treatment  as  possible. 

Next  to  impregnation  tieatments,  brush  treatments  with  a 
high-grade  coal-tar  creosote  are  recommended.  If  these  are 

208 


PROLONGING  THE  LIFE  OF  LUMBER  AND  LOGS        209 

used,  the  wood  should  first  be  thoroughly  air  seasoned  and  dry 
at  the  time  the  preservative  is  applied,  otherwise  little  or  no 
beneficial  results  will  be  secured.  Two  coats  are  better  than  one, 
and  in  all  cases  the  oil  should-preferably  be  brushed  on  hot  (about 
150°  to  175°  F.),  care  being  taken  to  soak  especially  all  joints, 
bolt  holes,  and  laps. 

In  timbers  which  decay  only  at  the  joints,  the  joints  only  need 
be  coated  with  hot  creosote,  the  rest  of  the  member  being  left 
untreated.  All  joints  made  in  timber  which  has  been  impreg- 
nated should  always  be  brush-coated  with  hot  creosote  if  these 
are  framed  after  treatment. 

Timbers  treated  with  creosote  cannot  as  a  rule  be  painted,  as 
the  paint  will  not  adhere  to  them.  They  will,  however,  be  turned 
a  deep  brown  which,  on  prolonged  exposure,  will  become  lighter 
in  color.  For  rough  construction,  the  oil  will  take  the  place 
of  paint,  and  in  this  connection  also  effect  a  saving. 

Methods  of  Treating  Lumber  for  Buildings,  Greenhouses,  and 
Cars. — In  general  lumber  used  in  buildings,  cars,  etc. ,  cannot  be 
creosoted  because  it  is  desirable  to  paint  it,  and  as  mentioned, 
paint  does  not  readily  adhere  to  creosoted  wood.  In  certain 
cases,  however,  this  is  not  necessary.  For  example,  sills  in  build- 
ings, beams  in  porches,  etc.,  where  the  wood  is  covered,  can  be 
profitably  treated.  Thus  the  sills  and  beams  used  in  constructing 
the  so-called  " Sanitary  floors"  in  the  South,  particularly  New 
Orleans,  are  impregnated  with  10  to  12  pounds  of  creosote  per 
cubic  foot,  and  very  good  results  obtained.  Even  in  silos,  if  it  is 
not  desired  to  paint  them,  creosoted  lumber  can  be  used  to  ad- 
vantage provided  it  is  permitted  to  air  season  before  the  silos  are 
filled. 

When  the  wood  is  to  be  painted,  a  treatment  with  one  of  the 
antiseptic  salts  is  recommended.  Zinc  chloride,  mercuric  chloride 
copper  sulphate,  or  sodium  fluoride  will  all  give  good  results.  As 
mercuric  chloride  and  copper  sulphate  cannot  be  used  in  steel 
cylinders,  it  is  necessary  to  soak  the  lumber  in  stone,  concrete, 
or  wooden  vats  containing  these  preservatives.  This  is  done  as 
described  under  the  Kyanizing  process.  These  salts  have  a 
further  disadvantage  in  that  they  will  attack  the  steel  in 
carpenters'  tools.  Zinc  chloride  and  sodium  fluoride  can  be 
handled  as  described  in  the  Burnett  process.  The  lumber  should 
then  be  air  seasoned  before  it  is  placed  in  the  building,  after 
which  it  can  be  handled  like  untreated  lumber.  Paint  of  all  colors 

14 


210        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

will  in  general  adhere  readily  to  wood  treated  with  the  salts  just 
mentioned,  and  will  aid  materially  in  holding  them  in  the  wood. 
Treatments  of  this  kind  are  recommended  particularly  for  such 
places  as  floors  and  columns  in  porches,  trim  around  the  eaves, 
bench  boards  and  sills  in  greenhouses,  roofs  in  dye  houses,  and  in 
fact,  all  places  where  the  wood  is  subject  to  decay,  and  where  it  is 
necessary  to  pain  it  with  light  colored  pigments.  Much  has  been 
written  of  "dry  rot"  in  buildings.  This  can  be  greatly  re- 
tarded or  prevented  by  the  treatments  described,  since  it  is  caused 
by  a  fungus.  In  all  cases,  the  lumber  should  be  framed  to  as 
near  the  exact  dimension  it  is  to  have  as  can  be  done  because 
any  subsequent  cutting  will  expose  the  untreated  interior  and 
hence  shorten  the  life  of  the  wood.  It  is  believed  that  there  is  a 
good  field  for  many  lumber  companies  to  operate  treating  plants 
for  preserving  wood  used  in  building  construction.  By  so  doing, 
woods  which  are  not  naturally  durable  could  be  made  to  compete 
with  the  more  expensive  and  naturally  durable  woods  like  cypress, 
cedar  and  redwood,  and  would  in  certain  cases  be  preferable  in 
that  some  of  them  possess  greater  strength.  Treatments  with 
the  above  salts  will  also  resist  insect  attack. 

The  life  of  untreated  wood  can  be  prolonged  in  many  cases  by 
keeping  a  circulation  of  dry  air  about  it.  Stagnant  air  in 
cellars  or  store  rooms  is  particularly  liable  to  start  decay,  and  it 
frequently  happens  that  by  simply  improving  the  ventilation, 
further  decay,  can  be  arrested.  Of  course,  when  untreated 
wood  is  used,  sap  wood  is  a  detriment  and  "all  heart"  pieces  are 
always  to  be  preferred.  In  certain  types  of  flooring,  creosoted 
planks  can  first  be  laid  and  then  faced  with  thinner  planks  of 
untreated  wood.  If  timber  is  set  subject  to  decay,  ordinary 
paint  will  seldom  arrest  the  decay  unless  all  surfaces  of  the  wood 
are  treated.  In  fact,  the  paint  may  actually  hasten  decay  in  some 
instances,  as  for  example,  when  only  one  or  two  surfaces  are 
painted  and  the  others  are  left  unpainted.  The  unpainted 
surfaces  will  absorb  moisture,  while  the  painted  surfaces  will 
retard  it  from  evaporating,  and  thus  the  wood  will  actually  have 
more  moisture  in  it  and  in  such  a  condition  be  more  susceptible 
to  decay.  This  is  a  common  occurrence  in  the  floors  of  outdoor 
porches,  the  upper  side  of  which  is  usually  the  only  surface 
painted. 

It  has  been  reported  that  dry  rot  in  factories  can  be  checked 
by  raising  the  temperature  in  the  rooms  to  120°  F.  or  more  for  a 


PROLONGING  THE  LIFE  OF  LUMBER  AND  LOGS        211 

few  hours.  The  author  is  unable  to  verify  these  reports  but 
believes  the  treatment  well  worthy  of  trial  by  those  troubled 
with  this  form  of  decay.  f>  ? 

Methods  of  Preserving  Logs  from  Decay. — It  is  very  difficult 
to  store  logs  with  bark  on  them  for  any  length  of  time  without 
their  being  attacked  by  decay.  This  is  particularly  true  of  logs 
having  much  sapwood,  like  the  gums,  sycamore,  maples,  birch, 
etc.  Decay  can  be  retarded  if  the  ends  of  these  logs  are  given  one 
or  two  coats  of  creosote  as  soon  as  possible  after  they  are  cut. 
The  same  should  be  done  wherever  the  bark  has  been  broken  off. 
If  it  is  simply  desired  to  retard  checking,  the  ends  of  the  logs 
should  be  coated  with  paint,  or  better  still,  hot  paraffin.  In  this 
way  the  logs  can  be  protected  at  a  cost  of  only  a  few  cents  per 
thousand  feet  of  lumber.  To  protect  logs  from  insect  attack,  it 
is  necessary  to  peel  them  or  soak  them  in  water.  In  special 
cases,  the  methods  described  below  might  be  used. 

Methods  of  Treating  Log  Cabins  and  Rustic  Furniture. — No 
satisfactory  rflethod  of  keeping  bark  on  wood  for  any  appreciable 
length  of  time  is  known,  particularly  if  the  bark  is  soaked  by 
rain  from  time  to  time.  Fungus  and  insects  'are  both  very  apt 
to  work  in  under  the  bark  and  cause  it  to  fall  off. 

Damage  of  this  kind  can  be  largely  prevented  by  cutting  the 
logs  in  late  autumn  and  piling  them  so  that  they  will  dry  as 
rapidly  as  possible  or  by  utilizing  them  immediately.  Even 
better,  but  more  expensive  and  troublesome  results  can  be  ob- 
tained by  cutting  the  logs  in  the  spring  and  stripping  them  in 
laps  of  bark,  which  at  this  season  peels  readily.  The  bark  can 
then  be  soaked  in  a  1  percent  solution  of  mercuric  chloride 
and  the  logs  used  directly.  After  the  logs  have  air- dried,  they 
can  be  brush  treated  with  one  or  two  coats  of  coal-tar  creosote  or 
carbolineum.  When  this  has  dried  for  several  days,  the  bark  can 
then  be  nailed  to  the  logs.  Treatments  of  this  kind  are  the 
most  effective  known.  Care  should  be  taken  in  handling  the 
mercuric  chloride  solution  as  this  is  extremely  poisonous,  and 
also  in  thoroughly  air-seasoning  the  treated  logs  so  that  the 
odor  of  oil  will  not  prove  objectionable. 

Rustic  furniture  should  be  kept  under  cover  and  dry.  Little 
or  no  trouble  will  then  be  experienced  with  decay.  Insects; 
however,  may  attack  it,  as  is  evidenced  by  little  mounds  of  saw- 
dust and  miniature  pin  holes  in  the  bark.  Sponging  such 
furniture  thoroughly  with  kerosene  or  benzene  will  usually 


212        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

kill  the  insects  and  stop  their  depredations.  Or  if  the 
holes  are  caused  by  larger  wood-boring  insects,  carbon  bisul- 
phide can  be  injected  into  the  holes,  which  should  then  be  im- 
mediately stuffed  with  putty,  or  a  similar  substance.  The 
offensive  odor  of  the  bisulphide  will  leave  the  wood  in  a  few  days. 


CHAPTER  XVI 
THE  PROTECTION  OF  TIMBER  FROM  FIRE 

The  use  of  wood  as  a  construction  material,  especially  in  con- 
gested centers  as  in  cities,  has  a  serious  objection  due  to  the 
comparative  ease  with  which  it  can  be  ignited  and  with  which 
it  burns.  The  objection  to  its  use  because  of  this  property  is 
rapidly  growing  and  will  undoubtedly  continue  to  do  so.  The 
fire  losses  in  the  United  States  are  enormous,  reaching  the  vast 
sum  of  $215,000,000  per  year.  Of  course,  all  of  this  is  not  due 
to  the  use  of  structural  wood,  as  the  contents  of  even  "  fireproof  " 
buildings  are  inflammable  and  are  frequently  destroyed.  A  few 
cities  have  already  passed  ordinances  prohibiting  the  use  of 
natural  wood  in  buildings  over  a  certain  number  of  stories  in 
height,  and  other  cities  have  specified  against  the  use  of  wooden 
shingles  within  their  more  congested  limits.  Such  action  has 
attracted  keen  attention  of  late  to  the  possibility  of  rendering 
wood  noncombustible.  This  problem  is  quite  different  from  the 
problem  of  protecting  wood  from  decay  and  has  to  do  almost 
entirely  with  the  control  of  the  gases  driven  off  from  wood  when 
heat  is  applied  to  it.  If  these  gases  can  be  diluted  with  a  non- 
combustible  gas  in  proper  proportions,  the  wood  will  charr  and 
not  burn.  On  the  other  hand,  if  these  gases  can  be  kept  from 
mixing  with  requisite  amounts  of  oxygen,  a  similar  result  can 
be  secured.  In  either  event,  the  original  properties  of  the  wood 
will  be  destroyed,  so  that,  strictly  speaking,  it  is  practically 
impossible,  if  not  impossible,  to  render  wood  " fireproof."  The 
best  that  can  be  expected  is  to  either  make  the  wood  noncom- 
bustible or  slow  burning.  The  temperature  at  which  natural 
wood  will  ignite  under  ordinary  conditions  is  about  500°  F.  The 
temperature  of  a  burning  building  is  estimated  at  about  1700° 
F.  The  ease  with  which  natural  wood  ignites,  therefore,  when 
subjected  to  such  high  temperatures,  is  readily  seen.  As  great 
progress  in  protecting  wood  from  fire  has  not  been  made  thus  far 
as  in  protecting  it  from  decay,  and  but  two  companies  are  now 
in  operation  in  this  country.  Progress  has  been  considerably 

213 


214        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

retarded  by  fraudulent  practices  on  the  part  of  defunct  companies 
claiming  to  "  fireproof "  wood,  and  by  contractors  who  claimed 
to  use  such  wood  in  their  construction.  Furthermore,  a  gross 
misunderstanding  exists  concerning  the  possibilities  of  render- 
ing wood  noncombustible,  which  has  often  led  to  the  drafting  of 
impracticable  specifications.  Much  work  remains  to  be  done  in 
perfecting  present  methods  and  in  enlightening  the  public  to 
what  can  reasonably  be  expected. 

The  chief  objections  raised  against  the  use  of  " fireproof ed" 
wood  aside  from  increased  cost  are  the  leachability  of  the 
chemicals,  their  corrosive  action  on  metals,  their  effect  on  the 
strength  of  the  wood,  and  their  action  on  paints  and  varnishes. 
Wood  impregnated  with  the  best  known  fire  retardent  chemicals 
cannot  be  set  in  wet  or  damp  situations  or  exposed  to  the 
weather,  as  the  chemicals  will  be  leached  from  the  wood.  Nails, 
hinges,  etc.,  in  contact  with  such  fireproof  ed  wood  will,  when  it 
becomes  damp,  be  corroded.  Wood  treated  with  these  chemicals 
is  rendered  more  brittle  than  wood  not  treated,  although  the  loss 
in  strength  can  be  greatly  decreased  by  proper  methods  of  treat- 
ing and  drying.  For  many  purposes,  as  in  trim  in  buildings,  the 
question  of  decreased  strength  should  have  little  or  no  serious 
consideration,  as  this  property  is  not  important.  Due  to  their 
hygroscopic  nature,  the  salts  are  quite  liable  to  keep  the  wood 
moist  and  hence  interfere  with  the  adhesion  of  paint  or  varnish. 

When  not  exposed  to  the  weather  or  unusual  dampness,  "  fire- 
proofed  wood,"  as  it  is  now  known,  has  given  very  satisfactory 
service.  It  retains  its  resistance  to  fire  for  long  periods,  and,  so 
far  as  its  other  properties  are  concerned,  behaves  in  much  the 
same  manner  as  untreated  wood. 

The  Theory  of  Rendering  Wood  Fire  Retardent. — Those  results 
which  have  been  most  successful  thus  far  have  been  founded 
on  one  or  more  of  the  following  theories: 

1.  To  cover  the  wood  with  a  chemical  which,  like  sodium 
silicate,  when  heated  will  fuse  over  the  surface  and  prevent  a  free 
access  of  oxygen  to  the  wood. 

2.  To  cover  the  wood  with  a  noncombustible  material  which, 
like  asbestos  or  metal,  will  prevent  a  free  access  of  oxygen  to  the 
wood  and  thus  produce  a  slow  distillation. 

3.  To  impregnate  the  wood  with  a  chemical  which,  like  borax, 
when  heated  will  liberate  water  vapor  or  steam,  thus  diluting  the 
combustible  gases  so  that  their  ignition  cannot  occur. 


THE  PROTECTION  OF  TIMBER  FROM  FIRE  215 

4.  To  impregnate  the  wood  with  a  chemical  which,  like  salts 
of  ammonia,  when  heated  will  liberate  a  noncombustible  gas, 
thus  diluting  or  combining  with  the  combustible  gases  so  that 
combustion  is  impossible.  '  jjfc 

Owing  to  their  manner  of  application,  these  various  theories 
can  be  classified  into  two  groups  of  treatment  which  may  be 
called  superficial  and  impregnation  processes. 

Superficial  Processes. — These  consist  in  protecting  the  surface 
of  the  wood  from  contact  with  flames.  If  the  protective  coating 
is  a  liquid  like  sodium  silicate,  it  is  simply  painted  onto  the 
wood  or  the  wood  is  dipped  into  it.  Such  treatments,  while 
effective  in  retarding  the  ease  with  which  the  wood  will  catch  on; 
fire,  are  not  conducive  to  best  results.  Other  superficial  proc- 
esses  consist  in  covering  the  exposed  surface  of  the  wood  with  a| 
noncombustible  material  such  as  asbestos  or  metal.  Unless  the 
covering  entirely  surrounds  the  wood,  the  temperature  of  the 
protected  face  may  become  so  high  as  to  cause  the  wood  to 
ignite.  When,  however,  the  covering  entirely  surrounds  the 
wood  the  protection  is  very  efficient  as  burning  is  almost  entirely 
excluded  and  only  charring  is  produced.  As  might  be  surmised 
from  its  manner  of  application,  this  method  of  treatment  has 
only  a  limited  use  and  is  quite  costly. 

Impregnation  Processes. — These  are  conducted  at  the  present 
time  in  much  the  same  manner  as  the  Bethell  or  Burnett  processes 
(see  description)  of  protecting  timber  from  decay.  They 
differ  from  them  in  two  respects:  (1)  different  chemicals  are 
used,  and  (2)  the  wood  is  generally  kiln-dried  after  the  chemicals 
have  been  forced  into  it,  in  order  to  remove  the  large  amount  of 
water  injected  into  it.  As  a  general  rule,  only  thoroughly  air- 
seasoned  wood  is  treated,  this  usually  in  the  form  of  rough  sawn 
lumber.  The  kiln  drying  of  "  fireproof ed"  timber  requires  a 
nice  adjustment  in  that  the  temperatures  used  must  not  be  so 
high  as  to  volatilize  the  chemicals  injected  or  cause  them  to  " pull" 
toward  the  surface.  Checking  and  warping  must  also  be  guarded 
against.  Any  efficient  kiln-drying  process  can,  however,  be 
employed  provided  it  is  properly  applied. 

Chemicals  Used.; — A  large  variety  of  chemicals  hve  been  tested 
by  various  experimenters  in  the  attempt  to  render  wood  non- 
combustible.  The  more  important  of  these  chemicals  thus 
tried,  either  alone  or  in  combination,  are:  Ammonium  sulphate, 
phosphate  and  chloride,  zinc  sulphate  and  chloride,  borax, 


216        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

cresylates  of  mercury,  lead,  copper,  iron,  and  zinc,  sulphate  of 
iron,  alum,  calcium  bisulphite  and  lime,  sodium  silicate,  oxalic 
acid,  potassium  and  sodium  carbonate.  Best  results  have  been 
secured  with  the  salts  of  ammonia,  borax,  and  sodium  silicate. 

"  Fireproofing "  tests  have  been  made  at  the  U.  S.  Forest 
Products  laboratory  on  noble  fir,  using  the  following  fire-retarding 
agents.1 


Strength  of  solution 

Amount  dry  salt  in- 
jected per  cubic  foot 
of  wood 

33  percent  solution,  sodium  carbonate  

11  pounds 

35  percent  solution  sodium  bicarbonate. 

11  pounds 

30  percent  solution  oxalic  acid 

10  pounds 

20  percent  solution  borax  
20  percent  solution  ammonium  chloride  

5  pounds 
5£  pounds 

CHEMICAL  FIRE  RETARDENTS 

Sodium  Carbonate. — Sodium  carbonate  did  not  prove  efficient 
in  retarding  combustion  (Fig.  24).  It  also  caused  a  marked 
weakening  of  the  wood. 

Sodium  Bicarbonate. — Sodium  bicarbonate  did  not  prove 
efficient  in  retarding  combustion  (Fig.  24),  and  also  caused  a 
marked  weakening  of  the  wood. 

Oxalic  Acid. — Oxalic  acid  did  not  prove  efficient  in  retarding 
combustion  (Fig.  24),  and  also  caused  a  marked  weakening  of 
the  wood. 

Borax. — Borax  was  of  considerable  value  in  retarding  com- 
bustion (Fig.  24).  The  dotted  curve  (G),  Fig.  24,  shows  the 
comparison  with  natural  wood  and  the  other  fireproofing  agents 
used.  The  points  determining  the  position  of  this  curve  were 
obtained  after  the  piece  had  become  charred  and  incandescent. 
A  small  amount  of  an  inflammable  gas,  probably  carbon  mon- 
oxide was  generated,  which  burned  with  a  small  blue  flame  on 
the  top  of  the  test  specimen,  but  only  with  the  aid  of  the  pilot 
light. 

Ammonium  Chloride. — Ammonium  chloride  proved  of  con- 
siderable value  in  retarding  combustion  (Fig.  24).  The  points 
determining  the  position  of  the  dotted  curve  (F),  Fig.  24,  repre- 
sent the  same  condition  as  was  described  under  borax.  How- 

1  From  Proceedings  American  Wood  Preservers'  Association,  1914,  by 
Robert  E.  Prince. 


THE  PROTECTION  OF  TIMBER  FROM  FIRE 


217 


ever,  ammonium  chloride  is  somewhat  hygroscopic  and  its  use 
may  be  restricted  for  this  reason. 

Commercial  Treatment.*— A  number  of  tests  were  made  on 
pieces  of  red  oak,  treated  by  <*  commercial  fireproofing  company 
with  a  solution  containing  ammonium  phosphate  and  ammonium 
sulphate.  The  strength  of  the  solution  was  not  known.  Am- 
monium phosphate  and  sulphate  proved  of  considerable  value  in 
retarding  combustion. 

Tests  to  Determine  the  Inflammability  of  Timber. — Several 
methods  of  testing  the  inflammability  of  wood  have  been  sug- 


195 
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212 
105 
a   143 
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a                                           \ 

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rax 

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100      125       150      115       200       225      250       275      300       326       360      375       400       425       450      475 
Temperature-Degrees  Centigrade 

FIG.  24. — Time  required  to  ignite  natural  wood  and  wood  impregnated  with 
fire  retardent  chemicals  when  subjected  to  various  temperatures. 

gested.  The  more  common  of  these  are  the  shaving  test,  crib 
test,  spot  test,  and  electric  furnace. 

Shaving  Test. — Shavings  planed  from  the  treated  wood  are 
placed  in  a  wire  basket  over  a  Bunsen  burner.  Notes  are  taken 
on  the  length  of  time  required  to  ignite  the  shavings,  the  character 
of  the  burning,  the  length  of  glow,  and  the  loss  in  weight  due  to 
the  burning  or  smoldering.  This  method  of  test  is  faulty  in  that 
the  wood  is  so  finely  divided  that  the  volatile  gases  are  readily 
driven  from  it  and  conditions  comparable  to  practice  are  not 
duplicated.  Furthermore,  it  is  difficult  to  get  concordant  results 
due  to  varying  air  currents  and  temperatures. 

Crib  Test. — So  called  because  small  splints  of  wood   about 


218        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

1/2  X  1/2  X  4  inches  are  cut  from  the  treated  wood  and  piled 
in  a  crib  over  a  Bunsen  burner,  the  flame  being  permitted  to 
pass  through  them.  While  better  than  the  shaving  test,  the 
method  is  also  open  to  similar  criticism. 

Spot  Test.— A  flame  (usually  of  illuminating  gas) l  is  played  over 
the  surface  of  a  treated  piece  of  wood.  The  depth  to  which  it 
charrs  or  burns  and  the  character  of  burning  or  glow  are  noted. 
The  temperature  of  the  flame  may  be  read  from  a  pyrometer,  the 
thermocouple  of  which  is  placed  against  the  wood  at  point  of 
test.  This  method  is  much  more  comparable  to  practice  and 
gives  good  indicative  results,  which,  however,  are  faulty  in  that 
they  are  difficult  of  duplication. 

Electric  Furnace.- — This  method  of  test  gives  concordant  results 
when  small  pieces  of  wood  are  treated,  and  enables  an  accurate 
comparison  between  various  treatments.  It  is  objectionable, 
however,  in  that  the  heat  is  applied  to  all  sides  of  the  test  speci- 
men and  usually  requires  that  the  treated  plank  be  cut  into  small 
sizes.  For  laboratory  work,  however,  this  method  of  testing  has 
been  found  very  satisfactory.  The  apparatus  consists  of  a  silica 
tube,  wrapped  with  nichrome  ribbon.  An  iron  tube  fitted  with 
a  mica  sight  is  cemented  below  the  silica  tube. 

The  specimen  of  wood,  after  being  lowered  into  the  silica  tube, 
is  heated  at  a  uniform  rate,  by  passing  24  amperes  of  electric 
current  through  the  nichrome  ribbon.  Temperature  readings  are 
obtained  from  a  thermocouple  placed  beside  the  specimen  and 
reading  direct  from  a  Hoskins  pyrometer.  A  pilot  light  is  used 
to  ignite  the  gases  distilled  from  the  wood.  Compressed  air  par- 
tially dehydrated  by  expansion  is  passed  through  the  apparatus, 
its  intensity  being  indicated  by  a  sensitive  liquid  manometer. 
The  temperature  of  ignition,  character  of  combustion  or  glow, 
and  loss  in  weight  due  to  the  burning  for  a  3-minute  period  is 
noted.  After  ignition  the  specimen  is  lowered  into  the  iron  tube, 
where  it  can  burn  of  its  own  heat. 

Cost  of  Rendering  Wood  Noncombustible. — The  cost  of  ren- 
dering wood  noncombustible  is  in  general  higher  than  to  protect  it 
from  decay.  As  has  been  mentioned,  most  effective  results  in 
firep roofing  wood  have  been  secured  by  injecting  chemicals  into 
it.  These  are  more  corrosive  than  the  common  preservatives  and 
hence  increase  plant  depreciation.  Then,  the  preservatives  thein- 

1  A  plate  heated  electrically  has  been  suggested  in  place  of  the  flame  as 
being  easier  of  control. 


THE  PROTECTION  OF  TIMBER  FROM  FIRE  219 

selves  are  comparatively  expensive.  Finally,  the  wood,  after  it 
has  been  treated,  must  generally  be  kiln-dried  to  avoid  loss  in 
time  and  checking  in  seasoning.  Taking  the  above  factors  into 
consideration,  the  cost  of  rendering  wood  fire  retardent  is  ap- 
proximately as  follows, when  chemicals  like  ammonium  phosphate, 
costing  about  8.5  cents,  and  ammonium  sulphate,  costing  about 
3  cents  per  pound,  are  used. 

ESTIMATED  COST  or  RENDERING  WOOD  NONCOMBUSTIBLE  PER  M.B.M. 

Cost  of  handling $2.00-  $3.00 

Plant  depreciation  and  maintenance 0 . 90-    2 . 00 

Chemicals 10.00-  18.00 

Kiln-drying 2.00-    4.00 


Total $14.90-$27.00 

The  lower  figure  of  $14.90  per  thousand  assumes  the  plant  in 
continuous  operation  and  the  consumption  of  chemicals  about  175 
pounds  per  M.B.M.  The  upper  figure  of  $27  covers  opera- 
tions which  are  not  continuous  and  allows  for  a  heavier  injection 
of  the  salts  into  the  wood. 

The  Effect  of  Zinc  Chloride  and  Creosote  on  the  Inflammability 
of  Wood. — Although  zinc  chloride  is  not  one  of  the  most  ef- 
ficient fire  retarding  chemicals,  nevertheless  wood  treated  with 
it  is  much  more  difficult  to  burn  than  untreated  wood.  This 
makes  zinc-chloride  treated  timber  of  particular  value  in  those 
locations  where  decay  is  rapid  and  danger  from  fire  important, 
as  for  example  in  coal  mines.  Timber  treated  with  zinc  chloride 
will  ordinarily  ignite  at  the  same  or  lower  temperatures  as  un- 
treated wood  but  will  burn  far  more  slowly.  This  is  due  in  a 
large  measure  to  the  hygroscopic  nature  of  the  salt.  Some  tests 
made  in  the  electric  furnace  above  described  at  the  U.  S.  Forest 
Products  Laboratory  on  zinc-chloride  treated  hemlock  gave  a 
temperature  of  ignition  of  287°  C.  as  against  320°  C.  for  untreated 
wood.  Only  19  percent  of  the  treated  wood  was  destroyed,  how- 
ever, as  against  29  percent  of  natural  wood. 

Much  discussion  has  occurred  concerning  the  inflammability 
of  wood  treated  with  coal-tar  creosote.  This  matter  was  also 
investigated  at  the  U.  S.  Forest  Products  Laboratory  and  it  was 
found  that  wood  freshly  treated  with  creosote  was  very  inflam- 
mable, but  that  its  resistance  to  burning  increased  with  its  age. 
This  is  undoubtedly  due  to  the  lighter  oils  volatilizing  from  the 


220        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

wood  and  leaving  the  heavier  oils.  When  tested  under  the  condi- 
tions analogous  to  the  zinc-treated  specimens  mentioned  above, 
freshly  creosoted  hemlock  ignited  at  a  temperature  of  173°  C.  and 
lost  40  percent  of  its  weight  in  a  3-minute  burning  period.  When 
allowed  to  air-season  for  90  days,  the  temperature  of  ignition  rose 
to  216°  C.  and  a  loss  of  only  27  percent  in  weight  occuired.  Many 
instances  showing  the  resistance  of  seasoned  creosoted  timber  to 
fire  have  been  repoited,  of  which  the  following  are  cited: 

After  the  Jacksonville  fire  the  creosoted  telephone  poles  were 
standing  in  good  condition  although  the  buildings  all  about  them 
had  been  destroyed. 

The  Stuyversant  docks  at  the  same  place  were  built  of  un- 
treated and  creosoted  timber.  The  latter  was  easily  extinguished 
while  the  former  was  completely  destroyed. 

In  Baltimore  the  creosoted  wood-block  streets  did  not  burn 
but  came  through  the  fire  better  than  pavements  of  asphalt  which 
melted  and  ran  down  the  sewers. 

The  author  saw  a  shaft  of  a  coal  mine  in  Pennsylvania  which 
had  caught  fire,  it  being  timbered  with  untieated  and  creosoted 
props.  Aftei  the  fire  was  extinguished  by  smothering  the  mouth 
of  the  shaft,  all  the  untreated  props  had  been  burned  to  such  an 
extent  as  to  be  useless  while  those  creosoted  were  simply  charred 
and  not  replaced. 

It  appears  that  the  creosote  in  timber  when  it  does  ignite  burns 
for  a  long  time  in  much  the  same  manner  as  oil  does  in  a  wick; 
hence  the  reason  why  the  wood  itself  is  so  slightly  consumed.  It 
must  not  be  construed  that  creosoted  timber  is  fire  resistant  in  the 
same  sense  that  zinc-treated  timber  is,  but  that  when,  thoroughly 
air  seasoned  it  burns  for  some  time  with  less  damage  to  the  wood 
than  untreated  wood. 


CHAPTER  XVII 

THE    PROTECTION    OF    WOOD    FROM  MINOR 
DESTRUCTIVE  AGENTS 

A  description  of  the  manner  in  which  these  minor  destructive 
agents  attack  wood  has  been  given  in  Chapter  II.  We  will  now 
consider  methods  of  protection. 

Alkaline  Soils. — While  it  is  well  known  that  certain  alkalies  will 
attack  wood  and  eventually  disintegrate  it,  there  is  no  positive 
evidence  which  shows  that  their  presence  in  the  so-called  " alkali 
soils  "  does  this.  It  is  quite  likely  that  the  alkali  is  not  sufficiently 
concentrated  or  heated  to  sufficient  temperature  to  cause  disin- 
tegration. In  all  cases  which  have  been  examined  by  the  author, 
such  as  deteriorated  wood  from  flume  pipes,  cross-ties  or  poles, 
fungus  was  always  present.  It  is  believed,  therefore,  that  if  the 
growth  of  the  fungus  is  prohibited,  the  deterioration  can  be  materi- 
ally reduced  or  eliminated.  In  other  words,  the  wood  should  be 
treated  for  decay,  the  process  to  be  selected  depending  upon  local 
conditions  as  already  described.  By  so  doing  it  is  quite  likely  that 
the  effect  of  the  alkali  in  the  coils  can  be  generally  disregarded. 

Birds. — The  destruction  of  structural  timber  by  birds  is  so  small 
as  to  warrant  little  comment,  and  certainly  does  not  justify  kill- 
ing them.  Woodpeckers  will  at  times  drill  holes  into  buildings 
and  poles,  and  the  size  of  the  holes  and  the  oddity  of  the  attack  has 
given  rise  to  an  exaggerated  idea  of  the  destruction  done.  When 
buildings  are  attacked,  they  are  generally  more  or  less  deserted  and 
usually  good  for  nothing  but  birds'  nests  at  best. 

The  so-called  destruction  in  poles  is  apparent  rather  than  real, 
as  has  been  shown  in  Chapter  II,  although  at  times  the  holes 
drilled  by  the  birds  may  cause  a  real  damage.  No  good  method  of 
preventing  such  attacks  is  known.  Creosoting  the  poles  under 
pressure  is  of  assistance,  although  the  birds  will  at  times  attack 
creosoted  poles.  Plugging  the  holes  is  of  no  value  as  the  birds 
will  drill  new  holes.  It  often  appears  to  be  a  matter  of  "life  or 
death,"  and  considering  the  great  good  and  little  real  damage  that 
they  do,  destruction  caused  by  birds  had  best  be  charged  as  an 

221 


222        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

operating  expense  and  borne  with  a  smile.  Nesting  boxes  can 
often  be  used  with  great  satisfaction,  if  hung  on  posts,  poles  or 
buildings,  and  thus  prevent  damage  (see  Plate  XXIII  Fig.  C). 
The  use  of  such  boxes  has  been  extensively  tested  in  the  Grand 
Duchy  of  Hesse,  where  in  2  years  all  the  boxes  were  inhabited. 

Sap  Stain. — To  be  efficient,  all  known  methods  of  protecting 
wood  from  sap  stain  must  be  applied  before  the  stain  enters 
the  wood  .  If  the  logs  are  stained  before  they  are  cut  into 
lumber,  no  satisfactory  process  is  known  for  removing  the  stain. 
Logs  should  therefore  be  cut  as  soon  as  possible  after  they  are 
felled,  particularly  during  warm  weather. 

The  most  effective  means  of  preventing  stain  is  to  kiln  dry 
the  lumber  immediately  after  it  has  been  sawed,  and  then  keep 
it  under  cover.  In  this  manner,  stain  can  be  entirely  prevented. 
This  method,  however,  is  generally  too  expensive  and  cumbersome 
for  all  but  the  best  grades  of  lumber. 

For  rough  lumber,  dipping  in  a  solution  of  bicarbonate  of 
soda  gives  best  commercial  results.  In  practice,  this  is  done  by 
having  the  freshly  cut  boards  cairied  through  a  tank  of  the  soda 
solution  on  their  way  to  the  sorting  table.  In  this  manner  no 
extra  expense  for  handling  is  required.  A  5  to  8  percent 
solution  is  usually  sufficiently  strong.  This  should  be  kept  warm 
by  means  of  a  steam  coil  in  the  bottom  of  the  tank,  which  can  be 
constructed  of  wood,  iron  or  concrete.  A  few  companies  are  now 
maufacturing  "  soda-dipping "  tanks  and  will  furnish  a  complete 
outfit  (see  Plate  XXII,  Fig.  A)  or  the  tanks  can  be  constructed  by 
an  ordinary  mechanic.  After  the  lumber  has  been  dipped  in  this 
manner,  it  should  be  piled  with  open  air  courses  so  that  it  will  dry 
rapidly. 

An  extended  series  of  tests  were  made  by  the  United  States 
Forest  Service  in  co-operation  with  the  Great  Southern  Lumber 
Company  at  Bogalusa,  La.,  in  which  pine  boards  were  dipped  in  a 
variety  of  solutions.  It  was  found  that  solutions  of  mercuric 
chloride,  varying  in  strength  from  about  0.2  to  0.3  percent/were 
most  effective  in  preventing  stain,  but  on  account  of  theii  very 
poisonous  nature,  cannot  be  generally  recojrimended. 

The  following  conclusions  are  drawn  from  these  tests:1 

1.  Freshly  cut  sap  lumber  when  stacked  in  the  yard  to  dry 
should  be  stacked  in  open  piles  to  permit  a  free  circulation  of  air. 
Boards  so  piled  season  in  about  half  the  time  required  for  those 

1  Circular  192  United  States  Forest  Service. 


PROTECTION  OF  WOOD  FROM  DESTRUCTIVE  AGENTS    223 

piled  in  close  piles.  Open  piles,  moreover,  are  not  so  severely 
attacked  by  insects  and  are  more  effectively  protected  against 
sap  stain. 

2.  In  commercial  ^work  sap  stain  can  be  most  effectively 
prevented  by  dipping  boards  in  solutions  of  sodium  bicarbonate. 
Such  solutions,  though  they  give  fairly  good  results,  leave  much 
to  be  desired.     The  strength  of  the  solution  should  be  determined 
by  the  severity  of  the  conditions  under  which  the  boards  are 
to  season,  but  in  general  it  will  require  from  5  to  10  percent. 
Care  should  be  taken  that  the  chemical  used  is  not  mixed  with 
adulterants. 

3.  The  best  results  in  preventing  sap  stain  were  secured  with 
mercuric  chloride  solutions,  but  on  account  of  their  poisonous 
nature  they  are  not  recommended  for  general  use. 

4.  The  solution  made  by  mixing  sodium  carbonate  and  lime 
was  not  as  effective  as  one  of  sodium  bicarbonate  alone.     More- 
over, it  had  a  greater  tendency  to  streak  the  surface  of  the  boards 
with  a  white  precipitate. 

5.  Solutions  of  magnesium  chloride,  calcium  chloride,  sodium 
hydroxide,  phenol,  copper  sulphate,  and  zinc  chloride  did  not 
prevent  sap  stain;  nor  did  sprinkling  the  boards  with  naphthalene 
flakes  give  satisfactory  results. 

6.  On  account  of  cheapness  and  facility  in  operation,  it  is 
recommended  that  sap-stain  solutions  be  applied  to  the  boards 
by  machinery.     If  this  is  done,  the  cost  of  treating  lumber  with 
solutions  of  sodium  bicarbonate  will  amount  to  from  about  7  to 
10  cents  per  1000  hoard  feet. 

7.  The  indications  are  that  shavings  planed  from  soda-dipped 
boards  do  not  burn  as  readily  as  those  from  untreated  boards, 
but  the  difference  in  inflammability  is  so  slight  that  for  com- 
mercial purposes  it  may  be  neglected. 

Sand  Storms. — The  destruction  of  timber  in  the  United  States 
by  sand  storms  is  insignificant.  Far  more  is  destroyed  by  wind 
and  sleet  storms  against  which  there  is,  of  course,  no  known 
method  of  protection  except  heavier  and  more  expensive  construc- 
tion. In  certain  portions  of  the  Southwest  the  wind  carrying 
sand  at  high  velocity  so  wears  away  poles,  stakes  and  posts  that 
renewal  is  sometimes  necessary.  (See  Plate  XXII,  Fig.  B .)  About 
the  only  practical  method  known  of  retarding  such  damage  is  to 
nail  planks  of  wood  or  sheets  of  metal  to  the  poles  and  posts  and 
after  these  have  been  destroyed,  replacing  them. 


CHAPTER  XVIII 

THE    STRENGTH    AND    ELECTROLYSIS    OF    TREATED 

TIMBER 

The  Effect  of  Air  Seasoning  on  the  Strength  of  Wood.— It 
has  been  stated  in  Chapter  IV  that  a  considerable  amount  of 
water  can  be  removed  from  green  wood,  without  affecting  its 
strength.  As  soon,  however,  as  the  water  begins  to  leave  the 
cell  walls  so  that  their  moisture  content  is  decreased,  the  strength 
of  the  wood  rapidly  increases.  This  is  shown  in  Fig.  109  where 
the  strength  of  wood  is  plotted  against  the  amount  of  water 
it  contains.  Prolonged  air  seasoning  removes  a  certain  amount 
of  water  from  the  cell  walls  and  hence  increases  the  strength  of 
wood.  The  amount  of  water  thus  removed  depends  upon  the 
temperature  and  humidity  of  the  surrounding  air  and  the  size 
and  kind  of  wood  being  seasoned.  For  example,  it  is  greatest 
in  warm  dry  air  (as  in  summer)  and  in  thin  boards  (1  inch  or  less 
in  thickness).  Material  of  this  kind  is  called  "air  dry  or  sea- 
soned" when  it  contains  about  8  to  12  percent  of  water.  If  dried 
to  lower  moisture  than  this  it  is  very  probable  that  the  wood  will 
re-absorb  moisture.  Air-dry  lumber  containing  8  to  12  percent 
of  moisture  is  therefore  seasoned  about  16  to  20  percent  below 
its  fiber-saturation  point  and  has  about  twice  the  strength  of  green 
wood.  On  the  other  hand  if  the  boards  are  larger,  say  6  to  10 
inches  in  thickness  it  is  very  likely  their  "  air-dry"  moisture  will  be 
15  to  20  percent  rather  than  8  to  12  percent.  Consequently 
their  strength  will  not  be  increased  to  the  same  degree.  It  is 
evident,  therefore,  that  the  term  "air  dry"  is  a  very  variable  and 
arbitrary  one.  If  now,  the  wood  is  dried  in  a  kiln  and  its  moisture 
reduced  to  say  2  to  3  percent,  its  strength  will  be  increased  con- 
siderably over  what  it  was  in  an  air-dry  condition.  Thus,  other 
things  being  equal,  the  more  moisture  there  is  removed  from 
wood,  the  greater  will  be  its  strength  (Fig.  25).  This  relation 
has  been  equated  by  Tiemann1  for  longleaf  pine  with  the  following 
formula: 

1  Bulletin  70,  United  States  Forest  Service. 

,224 


PLATE  XXII 


FIG.  A. — Type  of  soda  dipping  tank  manufactured  by  the  Lufkin  Foundry 

and  Machine  Co. 


FIG.  B. — Stake  damaged  by  sand  storms  in  southern  California.  Com- 
pare portion  in  the  ground  with  portion  above  ground.  (Photo  courtesy 
of  the  Am.  Tel.  &  Tel.  Co.) 

(Facing  page  224.) 


FIG.  C. — Section  of  an  experimental  track  laid  with   steel   ties.     (Photo 
courtesy  of  the  Ry.  Eng.  Ass'n.) 


FIG.  D. — A  fence  of  concrete  posts,  Madison,  Wis.     (Photo  courtesy  Na- 
tional Concrete  Machinery  Co.) 


THE  STRENGTH  OF  TREATED  TIMBER 


225 


C  =  G  (22.1  P2  -  1335  P  +  25,610) 
where  C  =  crushing  strength  in  pounds  per  square  inch 

G  =  specific  gravity  4of  dry  wood 

P  =  percent  of  moisture. 

On  account  of  the  wide  variability  in  the  structure  of  wood,  the 
equation  is  applicable  only  within  certain  limits,  and  will  not,  of 
course,  give  the  exact  strength  for  each  and  every  piece  of  wood, 
but  is  sufficiently  close  for  most  commercial  engineering  problems. 


2,800 
2,700 
2,600 
2,500 

•g  2'40° 
5  2,300 

|  2.200 

CO 

5  2,100 
I  2,000 
£  1,900 

?  1,800 
>> 

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5  1,600 
«  1,500 

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a 
1,300 

1,200 
1,100 
1,000 
900 

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15     20     25     30     35     40     45 

Moisture-Per  cent  of  Dry  Weight 


FIG.  25. — Moisture-strength  curves  for  longleaf  pine,  eastern  spruce  and 
chestnut.     Note  fiber-saturation  points. 

Lowering  the  moisture  content  of  wood  below  its  fiber-satura- 
tion point  produces  certain  phenomena;  the  more  important,  so 
far  as  strength  is  concerned,  being  shrinkage  and  cell  slitting. 
Both  of  these  vary  with  the  kind  of  wood,  the  degree  to  which 
it  is  seasoned,  and  the  manner  in  which  it  is  seasoned.  Conifers 
shrink  less  than  hardwoods,  and  the  drier  the  wood  the  greater 

15 


226        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  shrinkage.  Given  the  specific  gravity  of  a  piece  of  wood 
its  shrinkage  from  a  green  to  oven-dry  condition  can  be  fairly 
closely  approximated  from  the  following  logarithmic  equations 
developed  by  J.  A.  Newlin: 

Shrinkage  in  volume  percent  =  26.5  G1-00 

Radial  shrinkage  in  percent  =    9.5  G1  °° 

Tangential  shrinkage  in  percent  =  16.5  G1-00 
where  G  =  specific  gravity. 

When  water  leaves  the  cell  walls  it  sometimes  happens  that 
these  check  open  and  become  more  or  less  filled  with  microscopic 
slits  (Fig.  24).  These  slits  apparently  weaken  the  wood  but  their 
weakening  effect  by  no  means  offsets  the  marked  increase  in 
the  strength  of  the  wood  due  to  its  loss  of  water.  If  wood  which 
has  once  been  thoroughly  air- dried  is  resoaked  in  water  until  it 
contains  as  much  water  as  it  originally  had,  its  strength  will  be 
found  to  be  less  than  the  original  green  strength.  The  slitting  of 
the  walls  probably  has  much  to  do  with  this. 

From  the  above  discussion,  it  can  readily  be  seen  that  any 
treating  process  which  tends  to  keep  wood  dry  will,  provided  it 
does  not  in  itself  weaken  the  wood,  tend  to  increase  the  strength 
of  the  wood.  Thus  treatments  with  creosote  tend  to  retard  the 
absorption  of  water  and  hence  keep  the  wood  in  a  stronger  and 
more  resilient  condition  than  untreated  wood  or  wood  treated 
with  a  preservative  like  zinc  chloride.  This  is  of  decided  ad- 
vantage in  certain  cases,  as  in  paving  blocks,  and  is  undoubtedly 
one  reason  why  creosoted  blocks  have  resisted  wear  so  much 
better  than  similar  blocks  laid  untreated.  On  the  other  hand, 
objections  have  been  raised  to  the  seasoning  of  wood,  partic- 
ularly in  mines,  where  certain  operators  assert  that  they  prefer 
green  wood  to  dry  or  partially  dry  as  it  bends  more  and  gives 
better  warning  of  danger  from  rock  fall. 

The  Effect  of  Steaming  on  the  Strength  of  Wood. — Little  is 
known  concerning  the  effect  of  superheated  steam  on  the  strength 
of  wood,  but  from  our  knowledge  of  the  effect  of  temperature  on 
wood,  the  rapid  drying  of  wood  and  practical  operative  results 
with  superheated  steam,  it  appears  that  it  is  very  prone  to 
seriously  weaken  wood  and  render  it  brash  and  brittle. 

Saturated  steam  is  in  common  use  in  preparing  wood  for  treat- 
ment as  has  been  shown  in  previous  chapters.  Saturated  steam 
in  itself  does  not  dry  wood,  but  heats  it  so  that  drying  is  possible. 
In  fact,  while  the  wood  is  in  the  steam  it  may  actually  take  up 


THE  STRENGTH  OF  TREATED  TIMBER 


221 


water,  particularly  if  it  is  already  partially  seasoned.     This  is 
shown  in  the  following  table:  . 

TABLE  34. — INCREASE  IN  WEIGHT  OF  LOBLOLLY-PINE  TIES  DUE  TO 


STEAMING1 


Conditions  of  steaming 

Gain  in  weight  per  tie,  due  to  steaming 

Period 

Pressure  per  square 
inch 

Green  ties 

Air-seasoned 
ties 

Hours 

4 

4 
4 
4 
4 
6 
10 

Pounds 

10 

20 
30 
40 
50 
20 
20 

Pounds 
2.13 

Pounds 
5.1 
6.9 
6.3 
8.1 
4.3 
10.8 
10.7 

0.62 
1.12 

0.62 

1.00 

After  the  wood  has  been  heated  and  the  steam  around  it  removed, 
the  heat  units  stored  in  the  wood  will  evaporate  much  of  the 
water  it  contains  and  produce  a  condition  of  partial  dryness 
or  " seasoning."  A  vacuum  applied  immediately  after  the  steam 
bath  will  further  increase  the  drying,  since  it  lowers  the  tem- 
perature at  which  the  water  will  vaporize.  Common  practice, 
therefore,  is  to  steam  the  wood  and  then  apply  a  vacuum.  The 
important  items  to  consider,  in  so  far  as  the  effect  of  steaming 
on  the  strength  of  wood  is  concerned,  are  the  temperature  of  the 
steam  and  the  length  of  time  it  is  applied  to  the  wood.  The  best 
data  on  this  subject  known  to  the  author  is  contained  in  United 
States  Forest  Service  circular  39,  which  summarizes  the  results 
of  about  6000  tests.  Due  to  the  variability  of  the  wood  used 
and  the  complexity  of  the  problems,  it  is  probable  that  further 
tests  might  change  some  of  the  conclusions  there  drawn,  but  the 
essential  features  are  probably  correct.  In  general,  it  appears 
from  these  tests  that  steaming  at  high  temperatures,  or  lower 
temperatures  for  long  periods,  materially  weakens  the  strength 
of  wood.  The  extent  of  the  weakening  will  depend  upon  the  kind 
of  wood,  its  moisture  content  at  the  time  of  seasoning,  the 
character  of  the  wood  structure  such  as  density,  rate  of  growth, 
etc.,  and  the  manner  in  which  the  steam  is  applied.  Disregarding 
the  individual  effect  of  each  of  these,  and  lumping  them  all 
together,  the  effect  of  the  temperature  of  the  steam  and  the 
length  of  time  it  is  applied  is  shown  in  Table  35.2 

1  Circular  39,  United  States  Forest  Service. 

2  United  States  Forest  Service  Circular  39. 


228        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


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THE  STRENGTH  OF  TREATED  TIMBER       229 

In  this  table  the  word  " control"  refers  to  the  test  pieces  cut  from 
the  ends  of  the  ties  which  were  .left  untreated  in  order  to  furnish  a 
standard  of  comparison.  It  should  be  noted  that  these  pieces 
were  tested  immediately  after-treatment.  It  was  found  that  if 
they  were  air  seasoned  after  treatment  and  then  tested  they 
regained  a  large  part  of  their  original  strength.  Sufficient  reliable 
data  is  not  available  to  state  accurately  what  is  the  maximum 
temperature  of  steaming  or  maximum  duration  of  steaming  that 
should  be  used.  The  conclusion  drawn  from  the  tests  just  quoted 
was  that  "for  loblolly  pine  the  limit  of  safety  is  certainly  30 
pounds  for  4  hours,  or  20  pounds  for  6  hours."  It  is  well  known 
that  some  of  the  best  results  secured  in  the  treatment  of  wood  in 
this  country  have  been  obtained  from  timbers  (longleaf  pine 
piling)  which  were  steamed  at  higher  temperatures  and  longer 
periods  than  this,  hence  it  is  entirely  probable,  when  full  informa- 
tion is  available,  that  more  severe  steaming  treatments  will  be 
found  safe  and  practicable. 

The  Effect  of  Boiling  Wood  in  Creosote  upon  its  Strength. — 
If  wood  is  submerged  in  creosote  which  is  heated  above  the 
boiling  point  of  water  under  atmospheric  pressure  only,  the  water 
contained  in  the  wood  will  be  converted  into  steam.  Unless 
confined,  the  steam  will  escape  and  thus  the  water  content  of  the 
wood  will  be  reduced.  It  is  obvious,  therefore,  that  boiling  wood 
in  creosote  seasons  the  wood  and  is  quite  a  different  action  from 
steaming  wood,  which  as  already  described,  is  simply  a  means  of 
heating  it.  If,  however,  the  wood  is  heated  in  oil  under  pressure, 
the  action  should  be  similar  to  that  produced  by  steaming  it, 
since  the  pressure  will  prevent  the  water  from  vaporizing. 

It  is  well  known  that  rapidly  seasoning  timber  is  very  apt  to 
weaken  it,  because  it  tends  to  develop  checks  and  slits.  This  is 
particularly  true  of  woods  having  a  complex  structure  such  as 
the  oaks,  maples,  etc.  Without  definite  knowledge  we  should 
therefore  expect  to  find  a  decrease  in  the  strength  of  wood  boiled 
in  creosote,  particularly  if  the  boiling  reduces  the  moisture  in  the 
wood  much  below  its  fiber-saturation  point.  Information  on 
this  point  is  meager.  Some  green  Douglas  fir  bridge  stringers 
boiled  in  creosote  and  then  impregnated  with  the  oil  showed 
about  40  percent  loss  in  strength  over  similar  stringers  untreated. 
This  decrease  was,  apparently,  permanent,  because  a  year's 
seasoning  after  treatment  showed  approximately  the  same 
results.  One  example  does  not,  of  course,  prove  that  the 


230        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

weakening  was  caused  by  the  boiling,  as  it  may  have  been  due 
either  to  the  heat  or  the  oil.  The  shrinkage  of  timber  boiled 
in  oil  is  very  rapid  and  its  quite  possible  that  this  rapid  shrinkage 
may  produce  injury  by  setting  up  a  complex  series  of  stresses  in 
the  wood.  Whether  or  not  this  is  the  case  and  the  extent  to 
which  it  may  affect  the  various  woods  is  not  known  at  the 
present  writing. 

The  Effect  of  Preservatives  on  the  Strength  of  Wood.— This 
is  a  much  discussed  problem  on  which  little  conclusive  data  is 
available.  A  number  of  tests  have,  however,  been  made  and 
from  them  certain  deductions  can  be  drawn.  The  preservatives 
which  have  been  tested  are  creosote,  zinc  chloride,  and  crude  oil. 

Creosote. — It  has  commonly  been  supposed  that  creosote  does 
not  enter  the  cell  walls  of  wood  and  for  this  reason  could  have, 
per  se,  little  or  no  effect  on  the  strength  of  wood.  Careful  tests 
by  Teesdale1  have  shown  that  creosote  enters  the  cell  walls  and 
will  cause  them  to  swell.  The  amount  which  is  absorbed  by  the 
walls  in  practice  is,  however,  insignificant  compared  with  the 
total  amount  injected.  We  should  expect,  therefore,  that 
creosote  has  but  little  weakening  effect  on  the  strength  of  wood 
treated  with  it.  Tests  made  on  creosoted  wood,  tend  to  sub- 
stantitate  this  (Table  6),  these  being  made  on  small  clear  speci- 
mens impregnated  with  about  8  pounds  of  oil  per  cubic  foot.  Green 
loblolly  pine  steamed  and  creosoted  with  about  20  pounds  of  oil 
per  cubic  foot  showed  no  loss  in  strength  over  the  ties  which  were 
simply  steamed  and  then  tested.  In  fact,  in  creosoting  loblolly 
pine  without  steaming,  the  creosoted  wood  tested  higher  than 
the  untreated  wood,  the  process  apparently  having  a  tendency 
to  dry  the  wood.2  Some  full-sized  longleaf  pine  bridge  stringers 
steamed,  creosoted  by  the  Bethel  process  with  12  pounds  of  oil  per 
cubic  foot  and  then  tested,  showed  no  apparent  loss  in  strength 
over  the  stringers  tested  untreated  and  carefully  matched  with 
them.  It  appears  that  when  the  wood  is  not  damaged  by  the 
process,  creosote  in  itself  will  produce  little  or  no  weakening  of 
practical  significance.  There  is,  however,  a  possibility  that 
this  will  not  hold  for  all  kinds  of  wood  but  at  present  data  to 
substantiate  this  is  not  known. 

Zinc  Chloride. — It  is  well  known  that  a  concentrated  solution 
of  zinc  chloride  will  dissolve  wood.  In  practice,  the  solutions 

1  Circular  200,  United  States  Forest  Service. 

2  Circular  39,  United  States  Forest  Service. 


THE  STRENGTH  OF  TREATED  TIMBER       231 

rarely  exceed  a  strength  of  6  percent  and  at  this  concentration 
their  action  on  wood  is  very  slight.  The  common  specification 
calls  for  an  injection  of  a  half  pound  of  dry  zinc  chloride  per  cubic 
foot  of  wood.  Assume  the  wood  after  treatment  will  season  to 
10  pounds  of  water  per  cubic  foot  and  the  preservative  has  been 
diffused  through  it.  This  will  give  a  strength  of  only  5  percent. 
If,  however,  the  solution  only  penetrates  the  outer  fibers  of  the 
wood  and  the  zinc  chloride  concentrates  itself  in  these  fibers, 
it  may  reach  sufficient  strength  to  do  actual  harm.  In  this 
condition  the  wood  is  said  to  be  " burnt"  or  " killed"  and  is  in- 
variably the  result  of  poor  workmanship.  Proper  treatments 
use  as  weak  solutions  as  possible  in  order  to  get  the  requisite 
absorption,  and  thus  avoid  any  liability  to  injury  of  the  wood 
fiber.  Green  loblolly  pine  treated  with  zinc  chloride  solutions 
of  various  concentrations  and  then  tested  in  static  bending, 
compression  parallel  to  the  grain  and  in  impact  bending,  gave 
the  following  results  when  air  dried  to  about  13  percent  moisture.1 

Strength  of  Average  strength  in 

solution  percent  of  steamed  wood 

2.5 98.0 

3.5 95.1 

5.0 91.8 

10.0 91.8 

The  conclusions  drawn  from  these  and  similar  tests  is  that  zinc 
chloride  when  properly  injected  into  wood  will  not  weaken  it  to 
any  appreciable  extent  under  static  loading,  but  apparently  tends 
to  render  it  brittle  under  impact,  especially  when  strong  concen- 
trations are  used. 

Crude  Oil. — Crude  oil  when  heavily  injected  into  wood  ap- 
parently weakens  it.  Thus  some  loblolly  pine,  shortleaf  pine 
and  red  gum  ties,  impregnated  with  about  14  pounds  of  crude  oil 
per  cubic  foot,  gave  only  73,  72,  and  90  percent  respectively  of 
the  strength  of  the  same  kind  of  ties  untreated,  whereas  the  ties 
treated  with  creosote  and  zinc  chloride  showed  no  loss  whatever. 

The  Effect  of  Temperature  on  the  Strength  of  Wood.— Heat 
tends  to  weaken  wood,  cold  to  stiffen  it.  In  this  respect  wood, 
therefore,  behaves  like  a  plastic  material.  Tiemann2  has  made 
some  careful  researches  along  these  lines,  and  the  results  secured 
by  him  have  been  substantiated  by  further  tests.  He  has  soaked 

1  Circular  39,  United  States  Forest  Service. 

2  Bulletin  70,  United  States  Forest  Service. 


232        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

pieces  of  longleaf  pine,  spruce  and  chestnut  in  water  for  various 
periods  and  then  tested  them  at  various  temperatures.  The 
general  results  are  shown  in  Table  36.  The  tests  designated 
"cold"  were  made  when  the  wood  was  at  temperatures  ranging 
from  7°  to  19°  F.;  those  marked  "warm"  at  45°  to  68°  F.  An 
examination  of  all  the  results  shows  a  decided  increase  in  both 
the  strength  and  stiffness  of  the  frozen  pieces,  excepting  the 
very  dry  wood.  Of  course,  in  treating  operations  the  timber 
is  seldom  frozen,  although  this  at  times  occurs.  On  the  other 
hand,  the  temperatures  in  the  cylinder  frequently  rise  to  250° 
F.  It  is  doubtful  whether  this  is  sufficiently  high  to  cause  in  itself 
any  permanent  weakening  in  the  wood,  so  that  after  the  timber 
has  again  reached  atmospheric  temperature  no  weakening  due 
to  the  temperature  of  treatment  has  any  practical  significance. 


TABLE  36. — THE  EFFECT  OF  TEMPERATURE  ON  THE  STRENGTH  OF  WOOD 

(Specimens  about  2  X  2   X  5.75  inches1* 


Kind  of  wood 

How 

tested 

Moisture  at 
test,  percent 

Crushing  strength, 
Ib.  per  sq.  in. 

Modulus  of  elasticity, 
Ib.  per  sq.  in. 

Longleaf  pine. 

cold 

23 

6,440 

1,418,000 

warm 

24 

5,750 

1,360,000 

Spruce 

cold 

27 

4,060 

894,000 

warm 

22 

3,923 

753,000 

Chestnut 

cold 

68 

3,180 

708,000 

warm 

72 

2,622 

553,000 

THE  EFFECT  OF  PRESSURE  ON  THE  STRENGTH  OF  WOOD 

Pressures  used  in  treating  timber  are  all  far  too  low  to  cause 
any  weakening  of  the  wood.  A  pressure  of  200  pounds  per  square 
inch  is  about  as  high  as  is  ever  held  and  even  this  is  much  below 
the  crushing  strength  of  our  weakest  commercial  woods.  It  is 
quite  probable  that  the  wood  during  treatment  undergoes  a 
slight  decrease  in  volume  (less  than  0.5  percent  in  general  woods) 
due  to  the  pressure  used,  but  that  on  the  release  of  pressure  this 
is  fully  recovered. 

The  Effect  of  Various  Treatments  on  the  Strength  of  Wood.— 
We  have  now  considered  the  individual  effect  of  the  various  units 
in  the  treatment  of  timber  upon  the  strength  of  the  timber.  Let 
us  now  consider  their  combined  effect  as  shown  by  some  tests  on 
treated  wood.  For  this  information  we  are  indebted  to  Dr.  W.  K. 


THE  STRENGTH  OF  TREATED  TIMBER 


233 


Hatt,  who  tested  a  number  of  ties  treated  by  various  processes  at 
commercial  plants.  In  other  words,  no  attempt  was  made  to  study 
more  than  the  added  effect  of  all  factors  entering  into  the  treat- 
ment in  order  to  ascertain  whether  or  not  the  treatment  decreased 
the  strength  of  the  ties  over  similar  ties  untreated.  The  results 
of  these  tests  are  shown  in  Table  37. 

TABLE  37. — SHOWING  EFFECT  OF  TREATING  TIES  UPON  THEIR  CRUSHING 
STRENGTH  AND  SPIKE  HOLDING  PoWER1 


Kind  of  wood 

Treating 
process  used 

Crushing 
strength  at 
elastic  limit 
perpendicular 
to  grain  in 
percent  of  un- 
treated tie 

Resistance  to  spike  pulling 
in  percent  of  untreated 
tie  with  cut  spikes 

Cut  spikes 

Screw  spikes 

Untreated..  . 

100 

100 

173 

Burnettized. 

97 

98 

172 

Red  oak 

Lowry. 

104 

93 

163 

Rueping  

92 

93 

162 

Full  cell.... 

104 

101 

172 

Untreated..  . 

100 

100 

215 

Rueping  

99 

123 

209 

Loblolly  pine  .... 

Lowry  
Rueping  

104 
112 

94 
109 

219 
246 

Full  cell.... 

100 

84 

184 

Crude  oil...  . 

73 

53 

192 

Untreated..  . 

100 

100 

241 

Shortleaf  pine  

Rueping  
Full  cell.... 

103 
108 

100 
103 

209 
223 

Crude  oil...  . 

72 

45 

176 

f  Untreated..  . 

100 

100 

202 

Longleaf  pine.  .  .  . 

\   Rueping  

109 

100 

205 

[  Full  cell  .... 

101 

105 

270 

Untreated..  . 

100 

100 

228 

Red  gum.  .  .  . 

Rueping  
Full  cell.... 

97 
99 

102 
105 

222 
252 

Crude  oil  — 

90 

70 

270 

1  A  part  of  the  differences  in  strength  here  noted  are  due  to  varying 
moisture  contents  of  the  ties  and  the  fact  that  different  ties  had,  of  course, 
to  be  used,  it  being  impossible  to  keep  these  absolutely  uniform. 

Data  taken  from  experiments  made  under  the  direction  of  Dr.  W.  K. 
Hatt  and  published  in  the  bulletins  of  the  American  Railway  Engineering 
Association. 


234        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

It  will  be  noted  that  all  the  treatments  show  little  or  no  decrease 
in  strength  with  the  exception  of  crude  oil.  The  increases  noted 
may  be  due  to  superior  wood  in  the  treated  ties  or  to  their  having 
dried  out  more  than  the  untreated  ties  or  to  a  combination  of  these 
two.  Of  course,  all  these  conclusions  presuppose  that  the  treat- 
ments were  properly  made  and  are  normal.  Bad  management  on 
the  part  of  the  treating  engineers  would,  undoubtedly,  have 
yielded  entirely  different  results. 

The  Electrical  Resistance  of  Wood  Treated  with  Creosote  and 
Zinc  Chloride. — This  a  matter  of  considerable  importance  to 
steam  railroad  companies  in  the  operation  of  their  block  signals,  to 
electric  traction  companies  in  the  return  of  their  current,  and  to 
telephone  and  hydro-electric  companies  in  the  seepage  of  current 
carried  in  wires  over  their  poles.  As  is  usual  in  problems  of 
this  kind,  the  opinions  of  operating  men  vary  considerably,  and 
little  agreement  is  found.  Mr.  J.  T.  Butterfield  conducted  some 
interesting  and  valuable  experiments  on  this  problem  at  Purdue 
University  in  1910,  with  ties  treated  at  commercial  plants,  the 
following  information  being  taken  from  his  work: 

"The  resistance  was  measured  by  the  method  commonly  used 
for  measuring  the  insulation  resistance  of  electrical  machinery, 
namely,  by  means  of  a  direct-current  voltmeter  of  known  resist- 
ance. This  method  was  applied  in  two  ways.  (1)  The  contact 
surface  for  flow  of  current  in  the  ties  was  a  sawn  surface  as  nearly 
plane  as  possible.  Contact  pressure  of  250  pounds  per  square 
inch  was  applied  in  a  Riehle  Testing  Machine  by  means  of  sheet- 
iron  pans,  placed  one  above  the  other  and  filled  between  with 
dry  sand,  by  which  constant  surface  resistance  was  obtained. 
(2)  After  some  of  the  fundamental  laws  were  investigated,  the 
resistance  of  the  various  ties  was  compared  by  measuring  the  cur- 
rent flowing  between  two  spikes  driven  20  inches  apart  in  the 
face  of  each  tie.  Then  the  relation  of  these  latter  tests,  between 
the  two  spikes,  to  the  conditions  obtaining  in  a  full  tie  with 
rails  spiked  thereto  was  investigated. 

In  beginning  the  tests  the  principal  elements  which  cause  the 
resistance  to  vary  were  determined  and  investigated  in  the  follow- 
ing order: 

1.  Amount  of  moisture  present. 

2.  Kind  of  wood. 

3.  Treatment. 

4.  Direction  of  grain. 


THE  STRENGTH  OF  TREATED  TIMBER       235 

5.  Contact  pressure 

6.  Temperature. 

7.  Amount  and  time  of  current  flowing. 

8.  Dimensions  of  specimen.,.. 

Moisture. — The  important  effect  of  moisture  is  plainly  shown 
by  the  following  tables,  determined  by  the  testing-machine 
method : 


TEST  OF  RED 

OAK 

Zinc-chloride  treatment 

1.7  percent 

Percent  moisture 

Ohms  per  cu.  in. 

14.4 

3,370,000 

17. 

414,000 

19.1 

94,000 

27.4 

2,140 

35.7 

1,381 

47. 

1,310 

52.2 

1,100 

Untreated 

13.3 

5,020,000 

17.3 

784,000 

21.6 

198,000 

26.6 

136,300 

38.0 

7,100 

43.3 

6,440 

47.3 

5,070 

In  order  to  investigate  the  longitudinal  distribution  of  resistance 
through  a  tie,  a  number  were  cut  up  into  6-inch  lengths  and  the 
resistance  measured  parallel  with  the  grain.  The  results  plainly 
showed  that  there  was  an  enormous  resistance  at  the  ends  of  a 
tie,  which  may  have  a  uniformly  low  resistance  in  the  interior. 
The  cause  for  this  high-end  resistance  was,  of  course,  the  drying 
out  of  the  ends. 

KIND  OF  WOOD  AND  TREATMENT 

In  measuring  the  resistance  of  different  woods,  the  method 
used  was  that  of  determining  the  resistance  between  two  spikes, 
as  described  above.  The  ties  were  generally  tested  in  the  yard 
and  had  been  piled.  Some  were  covered  and  were  no  doubt  less 
dry  than  others.  Variation  in  resistance  of  untreated  ties  of 
same  species  is  to  be  accredited  to  moisture  variation.  Generally 
tests  of  5  treated  and  15  natural  ties  enter  into  the  average. 


236        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
LOWRY  CREOSOTE  PROCESS 

Resistance  Ratio  of, 

(megohms  per  half  tie)  treated  to 

Natural  Treated  natural 

Red  oak 0. 182  0.177  0.973 

RUEPING  PROCESS 

Loblolly  pine 5.58  5.05  0.91 

Shortleaf  pine 2.97  1.035  0.35 

Longleaf  pine  (very  dry) 5.4  6 . 05  1.12 

Red  gum 0.39  0.22  0.58 

Loblolly  pine 1.46  1.41  0.96 

FULL- CELL  PROCESS 

Loblolly  pine 2.94  1.00  0.34 

Shortleaf  pine 3.41  2 . 70  0 . 79 

Longleaf  pine 1.80  2.2  1.22 

Red  gum 0.225  0.28  1.24 

Loblolly  pine 4.47  0.905  0.20 

ZINC  CHLORIDE  PROCESS 

Red  oak...  0.08  0.0125  0.156 


DIRECTION  OF  GRAIN 

The  direction  of  the  grain  has  a  decided  effect  upon  the 
resistance  of  wood,  and  as  the  resistance  of  ties  was  taken  parallel 
with  the  grain,  little  consideration  was  given  the  question  aside 
from  the  following  tests: 

RESISTANCE  IN  MEGOHMS 

Kind  of  wood  Radial  to        Tangential  Percent 

3-in.  cubes,  Lengthwise  growth  to  growth 

_  .    _  .  moisture 

air  dried  rings  rings 

Natural  red  oak 0.0175  0.12  0.15  25 

Natural  red  oak..  0.0175  0.041  0.07  40 


CONTACT  PRESSURE 

The  study  of  the  effect  of  contact  pressure  on  a  number  of 
different  specimens  held  between  contacts  in  the  testing  machine 
and  involving  the  longitudinal  resistance  corresponding  to 
different  loads  developed  the  following  results.  As  would  be 
expected,  it  was  found  that  the  resistance  decreases  rapidly  with 
increase  of  contact  pressure. 


THE  STRENGTH  OF  TREATED  TIMBER 


237 


RED  OAK,  ZINC  CHLORIDE  TREATMENT,  3-iN.  CUBES 


Lengthwise  of  grain 
Lb.  per 
sq.  in. 
500.0 

278.0 
56.5 
22.2 

8.9 

3.3 

1.0 

0.0 


Air  dried 
Ohms 

175 

180 

220 

270 

460 

575 
1550 
5850 


RED  GUM,  NATURAL,  3-iN.  CUBES 

Lengthwise  of  grain  Air  dried 

55.5  26,400 

33 . 3  26,800 

22.2  27,700 

15.5  30,350 

11.0  32,700 

7.9  33,000 

5 . 5  39,400 

0.0  67,000 


TEMPERATURE 

Some  preliminary  tests  were  made  upon  the  ties  to  discover 
the  effects  of  temperature.  The  results,  although  not  capable 
of  representation  by  a  smooth  curve,  showed  that  the  resistance 
decreased  with  an  increase  of  temperature  in  a  nearly  direct 
proportion. 

RED  OAK 
Zinc  chloride  treatment — testing  machine  method.     End  of  grain 

Block  =  5X8X6  inch 
Temperature  =  average  of  six  thermometers 

Temperature,  Resistance, 

degrees  C.  ohms 

0 . 33  2500 

3.65  2100 

5.70  1945 

7.50  1820 

10.70  1560 

12.20  1270 

14.50  1050 

16.70  910 

21.00  670 

22.50  623 


238        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

ELECTROLYTIC  EFFECT 

While  measuring  a  low  resistance  in  the  testing  machine  with 
a  high  voltage  it  was  noticed  that  the  voltmeter  needle  tended 
to  fall  back  rapidly  if  the  circuit  was  allowed  to  remain  closed 
for  a  short  time.  This  pointed  to  some  kind  of  an  electrolytic 
effect,  and  some  tests  were  therefore  made  in  which  the  current 
was  allowed  to  flow  for  some  time  until  the  resistance  became 
nearly  constant.  Then  the  circuit  was  opened  and  the  specimen 
allowed  to  recover.  The  following  are  the  results : 


ELECTROLYTIC  EFFECT 

Natural  red  oak.    60  percent  moisture 

Time 

Volts 

Ohms  per 

cu.  in. 

0.00  sec. 

13.00 

1010 

0.15  sec 

12.80 

1130 

0.30  sec. 

12.70 

1190 

l.OOmin. 

12.61 

1248 

2  .  00  min. 

12.55 

1288 

3  .  00  min. 

12.50 

1320 

4.  00  min. 

12.47 

1340 

6  .  00  min. 

12.41 

1380 

Circuit  opened 

7.00  min. 

12.40 

1386 

8.  00  min. 

12.79 

1140 

9  .  00  min. 

12.86 

1101 

10.  00  min. 

12.92 

1056 

11.  00  min. 

12.92 

1056 

INFLUENCE  OF  VOLUME 

The  relation  of  resistance  to  the  dimensions  of  the  specimen 
was  plainly  showed  to  vary  the  same  as  with  any  conducting 
material. 

RED  OAK — ZINC  CHLORIDE  TREATMENT 

Length  Section  Resistance, 

ohms 

6  in.  3  sq.  in.  9,790 

9  in.  3  sq.  in.  16,030 

12  in.  3  sq.  in.  22,500 

15  in.  3  sq.  in.  35,500 

RED  OAK — NATURAL 

Length  3  in.    Cross  section  varied 
Cross  section,  sq.  in.  Resistance,  ohms 

9  6,000 

18  11,000 

27  16,000 

36  22,000 


THE  STRENGTH  OF  TREATED  TIMBER  239 

RELATION  OF  TESTS  BETWEEN  SPIKES  TO  ACTUAL  TIE 

A  few  tests  were  made  with.rails  spiked  to  a  whole  tie,  and  the 
resistance  measured  and  compared  to  the  resistance  of  spikes 
20  inches  apart. 

The  resistance  between  the  rails  spiked  to  the  whole  tie  was 
found  to  be  about  18  times  the  resistance  between  spikes 
driven  20  inches  apart  and  4  1/2  inches  in  the  face  of  the  tie. 

The  moisture  condition  of  the  surface  of  the  tie  was  artificially 
varied. 

H  =  The  percentage  increase  in  conductivity  between  rail  and 
tie,  due  to  rail  bearing.  For  example,  the  value  of  H  =  0.95 
for  oak  ties  is  found  as  follows: 

_1  1 

4-4 
H  = 


44800 

CONDUCTIVITY  OF  TIE  WITH  RAILS  SPIKED  THERETO  AS  COM- 
PARED WITH  SPIKES  ALONE 

Section  of  85-pound  Rail  Spiked  to  Ties  at  Standard  Gage  Distance.      No. 
6  is  Red  Oak.     No.  7  is  chestnut 

Condition  of  tie  Ohms.  H.          Percent. 

Dry;  spikes  only f  No.  6  44,800  0 . 95 

I  No.  7  9,500  2.16 

Dry;  with  rails /  No.  6.  44,400           

\  No.  7.  ,  9,300           

Wet  at  rail  bearing;  spikes  only f  No.  6.  43,700  0 . 93 

\No.7.  9,400  6.79 

Wet  at  rail  bearing;  with  rails (  No.  6.  43,300           

I  No.  7.  8,800 

Wet  all  over;  with  rails f  No.  6.  27,800           

I  No.  7.  7,760 

Bottom  of  tie  in  wet  gravel;  with  rail. . . .      No.  6.  10,270  .... 

Tie  in  moist  gravel  ballast;  with  rail No.  7.  4,350  .... 

Tie  in  very  wet  ballast;  with  rail f  No.  6.  6,780  7.68 

I  No.  7.  3,220  6.52 

Same  as  above;  spikes  only (  No.  6.  7,300  .... 

I  No.  7.  3,430 

The  resistance  of  the  bearing  between  a  newly  spiked  dry  rail 
and  a  dry  red-oak  tie  will  be  found  to  be  approximately  1  per- 
cent of  the  total  conductivity  of  the  tie,  but  after  the  spikes 
have  loosened  the  pressure  on  the  rail  bearing  is  about  the 


240        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

weight  of  rail  per  tie  divided  by  the  area  of  the  bearing.  This 
is  about  2  pounds  per  square  inch.  Such  light  pressure  means 
high  contact  resistance.  Considering  the  further  fact  that  the 
crosswise  resistance  of  a  tie  is  several  times  its  lengthwise 
resistance  pei  unit  of  length,  and  that  all  leakage  current  through 
the  rail  bearing  must  pass  through  a  considerable  amount  of 
cross-grain  resistance,  the  total  resistance  of  the  leakage  path 
between  rails  is  very  high. 

CONCLUSIONS 

The  results  obtained  tend  to  establish  the  following  conclusions : 
Timber  is  ordinarily  classed  with  the  nonconductors.  When 
dry  and  well  seasoned,  it  has  a  very  high  dielectric  strength  and 
practically  infinite  resistance.  When  green  or  moist,  however, 
timber  becomes  a  kind  of  electrolytic  conductor  of  comparatively 
low  resistance.  The  treatment  with  zinc  preservatives  has  the 
simple  effect  of  producing  in  the  wood  a  stronger  electrolyte  and 
hence  a  better  conductor  of  current. 

1.  The  resistance  of  timber  varies  directly  with  the  length 
and  inversely  with  the  cross  section. 

2.  The  resistance  of  timber  varies  almost  inversely  with  the 
amount  of  moisture  present,  between  the  limits  of  15  and  50 
percent. 

3.  The  resistance  of  timber  is  lowest  when  measured  along 
the  grain,  and  highest  when  measured  tangentially  to  the  growth 
rings. 

4.  When  treated  with  a  soluble  salt  such  as  zinc  chloride, 
the  resistance  varies  approximately  inversely  as  the  amount  of 
the  salt  present. 

5.  Treatment  with  such  a  soluble  salt  does  not  change  the 
behavior  of  the  resistance  with  respect  to  the  percent  moisture 
present.     Only  the  amount  of  the  resistance  is  changed. 

6.  The  resistance  of  timber  varies  almost  inversely  with  the 
temperature  between  the  limits  of  zero  and  50°  C. 

7.  The  resistance  of  nonporous  woods,  such    as    the  pines, 
is  higher  than  that  of  porous  woods,  such  as  the  oaks  and  red 
gum. 

8.  Treatment  of  timber  by  different  creosote  processes  does 
not  greatly  change  the  natural  resistance  of  the  timber. 

9.  Finally,  all  the  data  taken  goes  to  establish  the  view  that 


THE  STRENGTH  OF  TREATED  TIMBER       241 

the  conductivity  of  wood  is  due  primarily  to  the  presence  in  the 
pores  of  an  electrolyte  formed  by  an  aqueous  solution  of  the 
salts  found  in  the  natuiahtimber,  or  of  these  salts  and  others 
artificially  introducerd. 

Assuming  the  worst  condition  for  leakage  covered  by  the  test, 
i.e.,  red  oak  ties  treated  with  zinc  chloride  laid  in  wet  ballast 
and  with  wet  lail  bearings,  the  resistance  between  the  rails  of  a 
block  1  mile  in  length  would  approximate  30  ohms.  This 
would  permit  a  leakage  current  of  0.05  ampere  to  flow  with  the 
battery  voltage  of  1.5  volts.  The  leakage  loss  would,  there- 
fore, be  0.075  watt,  or  about  30  percent  of  the  power  required  to 
operate  the  relay.  This  sholud  not  seriously  interfere  with  the 
operation  of  signals,  as  leakages  up  to  60  percent  exist  without 
such  serious  interference. 

It  is  to  be  regretted  that  determinations  of  resistance  were  not 
made  with  wet  ties  or  with  ties  and  rails  paitially  immersed  in 
water,  as  is  sometimes  the  case  in  practice,  for  it  is  believed  that 
under  such  conditions  the  leakage  current  would  probably  be 
sufficiently  large  to  interfere  with  the  successful  operation  of 
relays. 

As  a  final  conclusion,  it  should  be  noted  that  since  the  above 
results  show  only  a  reduction  in  resistance  of  a  tie  of  from  26  to 
53  percent  when  treated  with  zinc  chloride,  depending  upon  the 
percentage  of  moisture,  while  a  change  of  resistance  by  the  ratio 
of  25  to  1  may  be  effected  by  varying  the  kind  of  wood,  a  change 
of  33  to  1  by  varying  the  pressure  upon  the  tie  sufficiently,  and  of 
3.7  to  1  by  temperature  changes,  it  follows  that  the  treatment  of 
ties  with  preservatives  should  not  interfere  with  the  operation  of 
signal  circuits,  except  possibly  in  exceptional  cases  in  which  the 
resistance  of  the  leakage  paths  is  abnormally  low  from  other 
causes." 

From  a  number  of  inquiries,  it  is  the  experience  of  several 
signal  engineers  that  little  or  no  difficulty  will  be  experienced  with 
zinc  treated  ties  if  the  distance  between  signal  blocks  is  not  too 
great  and  if  the  ties  are  not  laid  green.  Some  of  them  have 
shortened  the  distance  between  signals  to  about  1000  to  1200  feet 
and  report  complete  satisfaction.  Against  creosoted  ties  no  com- 
plaint on  this  account  is  made. 

A  number  of  traction  companies  state  that  the  zinc-treated 
ties  corrode  their  spikes  very  rapidly  and  for  this  reason  they  are 
opposed  to  using  them.  It  is  entirely  possible  that  this  will  occur, 

16 


242        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

especially  if  the  ties  are  liable  to  hold  much  moisture  and  are 
situated  a  long  distance  from  the  power  house.  Ties  which  can 
be  kept  fairly  dry,  and  can  be  laid  close  to  the  power  house  so  that 
the  return  current  will  be  through  them,  rather  than  away  from 
them,  should  give  little  trouble. 

The  leakage  in  current  in  poles  and  cross  arms  treated  with 
soluble  salts  should  be  very  slight  and  of  little  or  no  practical 
consequence  since  they  are  not  counted  upon  for  insulation, 
this  being  taken  care  of  by  the  insulators  themselves.  However, 
it  seems  entirely  probable  that  creosoted  poles  and  arms  will  tend 
to  resist  leakage  more  than  those  which  are  salt  treated  because 
they  will,  in  general,  contain  less  moisture.  As  already  stated, 
such  a  difference  can  at  most  have  little  practical  significance  and 
for  this  reason  treated  poles  can  undoubtedly  be  used  in  the  same 
manner  as  untreated  poles. 


"'CHAPTER  XIX 
THE  USE  OF  SUBSTITUTES  FOR  TREATED  TIMBER 

By  the  term  " substitute"  is  here  meant  a  mateiial  which  is 
offered  in  place  of  wood,  wood  having  been  the  standard.  Thus, 
although  wood  and  asphalt  are  both  used  extensively  for  street 
pavements,  asphalt  is  not  considered  a  substitue  for  wood  but  a 
competitor  of  wood.  On  the  other  hand  a  concrete  tie  is  a 
" substitute"  for  the  wood  tie.  With  this  distinction  in  mind, 
a  clearer  conception  of  the  inroads  being  made  by  other  materials 
can  be  had.  It  is  not  intended  to  discuss  in  this  chapter  the 
general  substitution  of  other  materials  for  wood  but  only  for 
treated  wood.  This  has  taken  place  in  a  wide  variety  of  products 
and,  in  certain  instances,  is  making  rapid  headway.  It  is  caused 
by  the  rise  in  the  price  of  timber,  the  demand  for  better  con- 
struction and  an  improvement  in  the  manufacture  of  the  sub- 
stitutes. 

Substitutes  for  Wood  Ties. — This  was  one  of  the  first  fields 
entered  and  thousands  of  dollars  have  been  spent  in  attempting  to 
find  a  satisfactory  substitute  for  wood  ties.  Ties  made  of  steel, 
concrete,  leather,  and  combinations  of  these  materials  have  all 
been  tested  both  in  this  country  and  abroad.  Best  success  has 
been  had  with  the  steel  ties,  but  their  introduction  has  been  very 
slow,  and  the  results  secured  from  them  by  no  means  all  that  is  re- 
quired. The  American  Railway  Engineering  Association  has  gone 
rather  extensively  into  this  problem  and  has  made  a  report  con- 
taining much  valuable  data. l  It  states  that "  an  improved  form  of 
steel  tie.  as  shown  in  Plate  XXII,  Fig.  C,  of  the  type  manufac- 
tured by  the  Carnegie  Steel  Co.  with  metal  plate  over  the.  insu- 
lating fiber  and  with  the  wedge  clip  rail  fastening,  seems  to  be 
very  promising."  A  few  railroads  report  satisfactory  experience 
with  the  steel  tie,  while  other  companies  have  discarded  them. 
The  general  consensus  of  opinion  at  present  seems  to  be  that 
these  ties  are  still  in  the  experimental  stage  but  worthy  of  trial. 

As  a  result  of  its  studies,  the  American  Railway  Engineering 

1  Bulletin  108,  American  Railway  Engineering  Association,  1909. 

243 


244        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Association  committee  concludes  "that  no  form  of  reinforced 
concrete  tie  has  been  made  which  is  suitable  for  heavy  and  high- 
speed traffic,  but  believes  a  properly  reinforced  concrete  tie,  with 
proper  fastenings,  may  be  found  economical  in  places  where  speed 
is  slow  and  where  conditions  are  especially  adverse  to  the  life  of 
wood  or  metal."  The  Lake  Shore  &  Michigan  Southern  Railroad 
placed  some  "Buhrer  Concrete  Ties"  in  its  track  at  Sandusky, 
Ohio,  in  1904.  There  were  no  renewals  up  to  1908  and  all  the 
ties  appeared  in  good  condition.  The  more  common  experience, 
however,  seems  to  be  like  that  of  the  Pennsylvania  Railroad,  which 
placed  500  of  these  ties  in  1903.  "  The  concrete  broke  and  crum- 
bled and  by  December,  1906,  all  had  been  removed  on  account 
of  breaking."  Kimball,  Percival,  Affleck,  Chenoweth,  Keefer, 
Hickey  and  Alfred  concrete  ties  tested  by  various  railroads  all 
cracked  or  crumbled  in  2  or  3  years  although  in  a  few  cases  longer 
lives  were  secured.  It  appears,  therefore,  that  a  satisfactory 
substitute  for  the  treated  wooden  tie  still  remains  to  be  found. 

Substitutes  for  Wood  Poles. — Iron,  concrete  and  glass  have 
been  tested  for  poles.  In  cities,  the  iron  pole  has  given  very  good 
use  and  has  very  largely  replaced  the  wood  poles.  However,  in 
the  larger  cities,  even  the  iron  pole  has  been  done  away  with,  ex- 
cept for  street  lighting,  its  place  being  taken  by  conduits.  Wood 
poles  are  still  used  in  large  quantities  in  towns  and  cities  and  in 
the  country  for  trolley,  telephone,  telegraph  and  high  power  trans- 
mission lines,  although  with  the  latter,  steel  towers  furnish  the 
best  construction.  Concrete  poles  are  largely  in  the  experimental 
stage  as  yet.  Poles  100  feet  or  more  in  length  have,  however,  been 
constructed  of  reinforced  concrete.  On  account  of  their  great 
weight,  high  cost,  and  difficulty  of  handling,  it  is  doubtful  whether 
concrete  poles  will  make  serious  inroads  on  wood  poles  for  years 
to  come,  except  perhaps  in  isolated  cases.  Concrete  poles  have 
not  been  in  service  long  enough  to  know  their  merits. 

Glass  poles  are  purely  an  experiment  and,  from  the  results 
secured  thus  far,  success  seems  doubtful. 

A  review  of  past  experiences  shows  that  only  in  large  cities  has 
any  material  been  successfully  substituted  for  wood  in  the  manu- 
facture of  poles,  and  that  no  substitute  which  gives  promise  of 
extended  usage  is  in  demand. 

Substitutes  for  Wood  Piling. — Wrought  iron,  cast  iron,  steel 
and  reinforced  concrete  have  all  been  used  for  piles.  Iron  in  all 
its  forms  is,  of  course,  free  from  attack  by  the  marine  borers. 


USE  OF  SUBSTITUTES  FOR  TREATED  TIMBER         245 

It  corrodes,  however,  when  driven  in  sea  water.  Wrought  iron 
apparently  corrodes  more  rapidly  than  steel  which  contains 
about  0.1  percent  of  carbon.  <x  Cast  iron  becomes  pitted,  the  iron 
being  gradually  dissolved  leavftig  the  carbon.  The  life  of  iron 
piles  is  not  known,  but  from  tests  made  by  various  investigators, 
it  appears  that  wrought  iron  and  steel  will  corrode  at  the  rate  of 
about  0.40  inches  per  100  years.  The  actual  usefulness  of  the 
pile  will  depend  largely  upon  the  extent  to  which  it  becomes  pitted 
and  apparently  this  varies  between  very  wide  limits. 

Reinforced  concrete  piles  have  been  used  since  1896  and  large 
numbers  have  been  placed  in  various  harbors  of  the  world. 
These  piles,  are  attacked  at  times  by  the  sea  water,  which 
disintegrates  them.  Furthermore,  alternate  freezing  and  thaw- 
ing have,  in  cases,  cleaved  off  much  of  the  concrete.  Yet  in 
spite  of  these  difficulties,  concrete  piles  possess  considerable  merit 
and  give  promise  of  being  perfected  to  an  extent  where  they  will 
prove  free  from  these  objections.  Concrete  piles  have  not  been 
used  sufficiently  long  or  driven  in  sufficient  numbers  and  under 
such  conditions  as  to  furnish  reliable  data  on  their  probable  life. 

Substitutes  for  Wood  Posts. — Considerable  progress  has  been 
made  in  manufacturing  concrete  posts,  and  several  railroads  in  our 
country  are  now  using  large  quantities  of  them.  The  cost  of 
making  the  posts  varies  from  about  16  to  25  cents  each.  Nothing 
is  known  of  their  life,  but  this  is  estimated  by  several  manufac- 
tures to  be  at  least  40  years.  Concrete  posts  are  heavy,  trouble- 
some to  make,  liable  to  be  thrown  by  frost  heave,  require  careful 
handling  and  have  other  ills,  but  in  spite  of  them  all,  they 
possess  much  merit,  particularly  because  of  their  durability  and 
appearance,  and  have  unquestionably  come  to  stay  and  their  con- 
sumption will  increase.  (See  Plate  XXII,  Fig.  D.) 

Posts  are  also  made  of  cast  iron,  iron  pipe  and  galvanized  sheet 
iron,  but  the  number  is  so  small  as  to  be  insignificant  and  prob- 
ably will  always  remain  so,  except  for  a  comparatively  few 
special  cases. 

Substitutes  for  Wood  Mine  Timbers. — Concrete,  masonry  and 
steel  have  all  been  substituted  for  wood  mine  timbers,  but  only 
in  isolated  cases.  Concrete  mine  timbers  are  very  expensive, 
their  installation  interferes  with  the  working  of  the  mine  and  in 
some  cases  they  are  crushed  before  they  become  "set."  It  is 
doubtful  if  they  will  come  into  general  use.  (See  Plate  XXII, 
Fig.  A.)  Iron  mine  "timbers"  have  been  tested  both  here  and  in 


246        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Europe.  They  are  expensive,  difficult  to  install,  and  are  corroded 
by  the  mine  gases  and  water.  Furthermore,  if  the  mine  once 
starts  to  "cave,"  the  iron  " timbers"  will  fail  although  they  will, 
of  course,  hold  a  greater  load  than  wood.  In  Europe  a  unique 
method  in  the  design  of  iron  props  has  been  tested.  It  consists 
of  two  hollow  pipes,  one  of  which  fits  snugly  inside  the  other. 
Round  iron  balls  are  then  placed  in  the  lower  pipe.  In  this  man- 
ner the  upper  pipe  can  be  extended  and  held  by  the  balls,  pre- 
venting further  telescoping.  When  it  is  desired  to  remove  the 
prop,  a  plug  in  the  lower  pipe  is  opened  and  the  balls  allowed  to 
roll  out.  This  makes  a  prop  which  can  be  fitted  into  place.  Its 
cost,  of  course,  is  high  and  in  addition  it  is  subject  to  most  of 
the  objections  raised  against  iron  mine  "  timbers."  Our  largest 
iron  and  steel  company  is  using  enormous  quantities  of  wood  in 
its  own  mines,  some  of  which  is  treated  with  preservatives. 
Masonry,  is,  of  course,  out  of  the  question  because  of  its  high 
cost,  trouble  in  laying,  etc.,  except  for  very  unusual  situations, 
so  it  doubtless  will  never  become  a  serious  rival  to  other  forms 
of  "timbering." 

Substitutes  for  Wood  Bridge  Timbers. — Steel,  masonry  and  re- 
inforced concrete  have  almost  entirely  replaced  wood  in  the 
construction  of  permanent  bridges.  In  addition  to  possessing 
greater  strength,  such  bridges  are  less  subject  to  destruction  by 
fire.  In  so  far  as  durability  between  steel  and  wood  bridges  is 
concerned,  doubt  still  exists  in  the  minds  of  some  engineers  and 
conflicting  data  have  been  submitted.  Creosoted  wood  bridge 
timbers  are  known  to  have  existed  in  perfect  condition  for  over 
30  years  in  the  South  where  decay  is  generally  rapid.  Appre- 
hension of  the  gradual  deterioration  ("fatigue")  of  such  timber 
due  to  repeated  impacts,  does  not  appear  well  founded.  Some 
railroads  in  our  country  are  laying  creosoted  bridge  timbers  on  top 
of  steel  members,  thus  adding  to  the  elasticity  of  the  bridge  and 
deadening  of  sound.  Considerable  quantities  of  wood  are  still 
used  on  steel  bridges  in  the  form  of  ties,  guard  rails,  wall  plates, 
etc.,  and  in  wooden  bridges  and  trestles,  but  as  the  demand  for 
high  grade  permanent  structures  increases,  the  use  of  wood  will 
unquestionably  decrease.  It  is  likely,  however,  that  a  demand 
for  wood  shields  under  steel  bridges  which  are  subject  to  corro- 
sion from  the  locomotive  stacks  will  increase,  especially  when  the 
wood  is  rendered  noninflammable. 


PLATE  XXIII 


FIG.  A. — Concrete   mine    props,    Pennsylvania.     (Forest    Service    photo.) 


FIG.  B. — Indiana  Tie  Company's  wood  preserving  plant,  Joppa,  111. 
Note  depressed  tracks  and  manner  of  running  cylinder  cars  on  flat  cars  for 
loading  ties  into  box  cars  for  shipment. 

(Facing  page  246.) 


PLATE  XXIII 


FIG.  C. — Nest  box  used  to  protect  poles  and  buildings  from  attack  by 
woodpeckers.     (Photo  courtesy  Ernest  Baynes.) 


Fia.  D. — Wood  dowels  screwed  into  softwood  ties  as  a  protection  against 

spike  cutting. 


USE  OF  SUBSTITUTES  FOR  TREATED  TIMBER        247 


Substitutes  for  Wood  in  Buildings  and  Cars. — As  only  small 
quantities  of  treated  wood  are  used  in  the  construction  of 
buildings  and  cars,  the  substitution  of  other  materials  affects  but 
little  the  wood  preserving  industry. 

A  special  committee  of  the  American  Railway  Association  ap- 
pointed in  1912  circularized  the  railroads  of  the  United  States 
and  received  reports  from  247  railroad  companies  operating 
227,754  miles  of  track.  The  object  of  the  circular  was  to  ascer- 
tain the  progress  being  made  in  introducing  steel  passenger  cars 
in  place  of  wooden  cars.  The  following  table  summarizes  the 
findings  of  this  committee: 


Total 
number 

Steel, 
percent 

Percentages 
steel  Uner 
frame 

Wood, 
percent 

1909  
1910 

1880 
3638 

26.0 
55  4 

22.6 
14  8 

51.4 

29  8 

1911  

3756 

59.0 

20.3 

20.7 

1912  
January,  1912 

2660 
1649 

68.7 
85  2 

20.9 
11  5 

10.4 
3  3 

(Under  construction) 

The  substitution  of  steel  for  wood  in  freight  cars  is  also  taking 
place  at  a  rapid  rate.  While  opinions  vary  widely  at  present,  it 
appears  that  a  combination  of  steel  and  wood  will  be  the  ultimate 
solution  of  many  of  the  freight  car  problems.  Similar  changes 
are  taking  place  in  the  construction  of  buildings  in  cities  where 
the  tendency  is  to  reduce  the  fire  hazard  to  a  minimum.  Steel, 
concrete,  and  clay  products  have  replaced  wood  to  a  very 
large  extent  and  there  is  little  doubt  but  what  such  replace- 
ment is  permanent.  In  certain  cases,  however,  a  reaction  has 
set  in,  as  it  was  found  that  many  buildings  supposedly  "  fire- 
proof "  were  really  not  so  when  put  to  the  test.  Thus  wood 
floors  and  trim  will  probably  remain  for  years  to  come.  "Slow 
burning"  factory  construction  has  also  been  in  demand.  It  is 
believed  that  "  fireproofing  "  wood  used  in  such  buildings  will  do 
much  to  remove  some  of  the  serious  objections  raised  against 
wood  and  that  this  phase  of  the  wood-preserving  industry  will 
grow  to  much  larger  proportions  than  at  present. 

Substitutes  for  Wood  Shingles. — There  is  a  great  variety  of 
roofing  materials  such  as  metal,  slate,  tile,  asbestos,  etc.,  now  on 
the  market  which  are  replacing  shingles.  This  has  been  brought 
about  largely  through  the  demand  for  fireproof  construction — 


248        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

certain  cities  having  passed  ordinances  prohibiting  the  use  of 
wood  shingles  within  their  congested  limits.  As  buildings  be- 
come more  crowded  and  permanent,  wood  is  invariably  replaced. 
In  general,  roofs  built  of  these  " substitute"  .materials  cost  more 
than  shingle  roofs,  not  only  for  the  covering  itself,  but  for  the  con- 
struction necessary  to  hold  up  the  greater  weight.  It  is  possible 
that  the  progress  being  made  in  "fireproofing"  shingles,  will  do 
much  to  retain  their  existence.  If  this  one  very  serious  objection 
could  be  removed,  wood  shingles  would  remain  in  favor.  They 
possess  certain  characteristics  such  as  cheapness,-' ease  of  repair, 
light  weight,  adaptability  to  artistic  design,  durability,  resistance 
to  heat  transmission,  etc.,  which  are  in  strong  demand. 

Substitutes  for  Wood  Conduits  and  Pipes. — The  use  of  treated 
wood  for  these  purposes  is  quite  small,  and  forms  but  a  small 
percentage  of  the  total  amount.  Fiber  conduit,  tile,  brick,  and 
steel  are  all  used  in  large  quantities.  Creosoted  wood  conduit  is 
very  durable  and  has  given  excellent  service.  It  is  comparatively 
inexpensive,  easily  laid  and  resistant  to  injury  from  settlement 
of  the  surrounding  earth.  The  oil  will,  of  course,  attack  rubber 
and  under  certain  conditions  cannot  be  used.  Large  quantities 
of  wood  have  been  used  in  building  pipes,  particularly  for  irrigat- 
ing purposes.  One  decided  advantage  seems  to  be  a  lowering  in 
the  coefficient  of  friction  through  use — a  result  quite  the  opposite 
of  metal,  which  tends  to  become  rough  and  hence  decrease  the 
quantity  of  water  which  flows  through  it. 


CHAPTER  XX 
APPENDICES 

Minor  Wood-preserving  Processes. — No  attempt  is  made  to 
list  and  describe  all  of  the  various  processes  which  have  been 
advanced  in  this  country  to  preserve  wood  from  decay.  To  do  so 
would  prolong  this  book  to  several  volumes.  Some  idea  of  the 
number  of  wood-preserving  processes  suggested  can  be  gained 
by  examining  the  list  of  patents  given  below.  But  to  inform  those 
who  might  wish  information  on  this  phase  of  wood  preservation, 
a  number  of  the  better-known  and  more  interesting  methods 
will  be  briefly  discussed.  Some  of  them  may  eventually  be 
extensively  practised  in  our  country. 

Thilmany  Process. — Patented  by  Thilmany  in  1876,  the  proc- 
ess consists  in  impregnating  wood  with  copper  sulphate  (later 
zinc  sulphate  was  substituted)  followed  by  a  second  injection  of 
barium  chloride.  The  object  was  to  produce  a  chemical  reaction 
giving  copper  chloride  and  barium  sulphate;  the  latter  being 
insoluble  in  water  was  intended  to  plug  the  wood  and  prevent  the 
copper  chloride  from  leaching  out.  The  process  was  tested  by 
several  railroads  in  this  country  without  apparent  success. 

The  B-M  Timber -preserving  Process. — This  process  uses 
a  combination  of  zinc  chloride  and  aluminum  sulphate  as 
covered  by  patents  held  by  Hubertumuhle  of  Schopfurth, 
Mark,  Germany,  It  is  claimed  that  the  aluminum  sulphate  is 
not  only  an  antiseptic  salt,  but  gives  a  better  solution  to  the  zinc 
chloride  and  carries  this  salt  deeper  into  the  wood.  It  is  also 
claimed  to  combine  in  part  with  the  wood  structure.  The 
solution  is  injected  into  timber  much  in  the  same  manner  as  zinc 
chloride  in  the  Burnett  process  except  that  the  temperatures  are 
kept  somewhat  lower.  From  analyses  of  treated  wood  made  by 
certain  reputable  chemists,  it  appears  that  better  penetrations  are 
secured  in  the  B-M  process  than  in  the  straight  Burnett  process. 
Some  treating  companies  in  the  United  States  are  now  ready  to 
treat  timber  by  this  process. 

249 


250        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

The  Goltra  Process. — Named  after  W.  F.  Goltra  of  Cleveland, 
Ohio.     For  handling  ties  the  distinct  steps  in  the  process  are: 
(a)  Steaming  ties  upon  delivery  at  plant. 
(6)  Stacking  ties  for  open-air  seasoning. 

(c)  Machining  ties. 

(d)  Drying  and  warming  ties  in  ovens. 

(e)  Impregnation  with  antiseptic  liquid. 

The  novel  features  in  the  process  are  the  steaming  of  the  ties 
on  delivery  at  the  plant  and  then  air  -  seasoning  them;  also 
warming  the  ties  in  ovens  before  injecting  the  preservative.  So 
far  as  the  author  knows,  this  process  is  not  in  commercial  use, 
although  it  has  been  considerably  agitated  in  the  past  few  years. 

The  Hasselman  Process. — Patented  in  the  United  States  in 
1897.  This  process  consists  essentially  in  injecting  into  wood 
a  solution  containing  sulphates  of  iron  and  aluminum  to  which 
"Kainit"  is  added  to  neutralize  the  free  acids  which  may  be 
formed.  The  process  was  tested  experimentally  in  Texas  with 
poor  results.  Since  then  certain  modifications  of  the  process 
have  been  proposed  by  Barschall  and  some  timber  treated  in  this 
manner  is  now  under  test  by  the  United  States  Forest  Service 
with  no  conclusive  results  to  date. 

The  Creo-Resinate  Process. — First  practised  by  the  United 
States  Wood  Preserving  Company,  particularly  for  the  treatment 
of  paving  blocks.  The  wood  is  subjected  to  a  dry  heat,  after 
which  a  vacuum  is  drawn  and  the  creo-resinate  mixture  forced 
into  the  wood.  This  mixture  consists  of  creosote  (about  50 
percent),  48  percent  rosin,  and  2  percent  formaldehyde.  A 
subsequent  treatment  with  a  solution  of  lime  is  then  given.  It  is 
understood  that  the  original  treatment  has  undergone  considerable 
change  since  it  was  first  advocated. 

Robbins'  Process.— Practised  by  the  Suffold  Wood  Pre- 
serving Company  of  Boston  about  1869.  It  consisted  in  passing 
vapor  of  naphtha  into  the  retort  after  the  wood  had  been  run  into 
it,  the  vapor  being  heated  to  about  250-300°  F.  This  vapor 
was  to  expel  the  water  from  the  wood,  coagulate  the  albumen, 
and  expand  the  wood  pores.  The  temperature  in  the  retort 
was  then  raised  to  400°  F.  and  vapor  of  creosote  passed  into  the 
wood.  The  process  was  tested  extensively,  but  failed. 

Powell  Process. — This  is  an  English  process  which  has  been 
tested  extensively  abroad  but  is  little  known  in  our  country. 
It  consists  in  boiling  wood  in  a  solution  of  sugar  for  a  few  hours 


APPENDICES  251 

and  then  drying  it  in  an  oven  at  high  temperatures.  It  is  said 
to  render  wood  resistant  to  ants  and  decay  and  nonabsorptive 
to  water.  Tests  known  to  the  author  indicate  the  process  has 
decided  merit  in  overcoming  4he  hygroscopicity  of  wood. 

Creoaire  Process. — Advertised  by  the  International  Creosot- 
ing  &  Construction  Co.  It  consists  in  treating  wood  similar 
to  that  employed  in  the  full-cell  creosote  process,  but  after  the 
desired  amount  of  oil  is  forced  into  the  timber  the  cylinder  is 
drained  of  excess  oil  and  an  air  pressure  applied  to  drive  the  oil 
further  into  the  wood,  thus  producing  an  " empty-cell"  effect. 
Tests  made  by  the  author  show  that  this  method  drives  con- 
siderable oil  out  of  the  wood  and  may  cause  "  bleeding." 

Vulcanizing  Process. — Practised  by  the  New  York  Vulcaniz- 
ing Company  of  New  York  City.  Sometimes  called  "  Raskins' 
process."  The  timber  is  placed  in  the  treating  cylinder.  Air 
compressed  to  150  to  200  pounds  per  square  inch  is  then  forced 
into  the  wood  through  a  water  separator  to  remove  moisture, 
and  heated  to  about  400  to  500°  F.  for  about  8  hours.  The 
process  rapidly  removes  the  water  from  the  wood,  and  producing 
a  partial  distillation,  is  claimed  to  render  it  antiseptic.  A  large 
number  of  ties  have  been  treated  by  this  process,  some  of  which 
gave  long  service. 

Cresol-calcium  Process. — This  is  a  Swedish  process  not 
practised  in  this  country  except  experimentally.  Agents  are 
Blagden-Waugh  Company  of  London.  The  timber  is  handled 
much  as  in  Burnettizing  except  that  the  solution  consists  of  a 
mixture  of  milk  of  lime  and  crysilic  acid  resulting  in  calcium 
crysilate.  It  is  under  test  in  several  places  in  the  United  States 
but  apparently  with  little  success. 

PATENTED,  PROPRIETARY,  AND  MINOR  WOOD  PRESERVA- 
TIVES USED  IN  THE  UNITED  STATES 

A  number  of  wood  preservatives  which  fall  under  this  heading 
are  used  in  the  United  States,  few  of  them  in  any  appreciable 
amount.  Perhaps  the  best  known  are  the  "carbolineums," 
which  are  used  quite  extensively,  especially  for  brush-treating 
timber. 

Cresol-calcium. — This  is  handled  by  Bladgen-Waugh  & 
Company,  London,  England,  Messrs.  Heidenstam  and  Freid- 
mann  being  the  inventors.  It  has  been  tested  experimentally 


252        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

in  the  United  States  but  is  not  used  commercially  here.  The 
results  secured  thus  far  have  not  been  very  satisfactory.  The 
preservative  consists  essentially  of  cresol  ("tar  acids")  and 
milk  of  lime  mixed  in  varying  concentration  up  to  15  percent  in 
strength  and  impregnated  in  a  manner  similar  to  Burnettizing. 

S.  P.  F.  Carbolineum. — Handled  by  Bruno-Grosche  &  Co. 
of  New  York  City.  It  is  a  preservative  distilled  from  tar,  which, 
according  to  the  engineering  department  of  the  American  Tele- 
phone and  Telegraph  Company,  is  somewhat  similar  on  distil- 
lation to  Avenarius  Carbolineum.  It  has  been  used  in  this 
country  for  many  years  and  has  given  good  results. 

Avenarius  Carbolineum. — Made  in  Germany,  but  handled  by 
the  Carbolineum  Wood  Preserving  Company  of  Milwaukee, 
Wis.,  and  other  cities.  It  is  essentially  a  high-grade  distillate 
of  coal-tar  specially  manufactured  and  has  been  used  in  this 
country  for  many  years  with  good  results. 

C -A -wood  Preserver. — A  foreign-made  product  handled  in 
this  country  by  the  C-A-Wood  Preserver  Company  of  St.  Louis, 
Mo.,  with  agencies  in  other  cities.  Essentially  a  high-grade 
distillate  of  coal-tar,  which  has  been  used  in  this  country  for  many 
years  with  good  results. 

Timberasphalt. — Sold  by  the  Indian  Refining  Company  of 
New  York  City.  It  is  an  "asphaltic  flux"  resulting  from  the 
refining  of  crude  oil,  and  has  no  marked  antiseptic  properties, 
relying  more  on  its  waterproofing  and  "plugging"  action  to 
preserve  wood.  It  is  one  of  the  more  recent  preservatives 
placed  on  the  market. 

Preservol. — Sold  by  the  Newbold  Manufacturing  Company, 
135  Greenwich  Street,  New  York  City.  Said  to  be  a  "creosote" 
made  from  beech.  It  has  not  been  very  extensively  tested  in  this 
country. 

Copperized  Oil. — Handled  by  the  Copper  Oil  Products  Com- 
pany of  New  York  City.  It  is  an  oil  containing  copper.  The 
kind  of  oil  used  and  amount  of  copper  it  contains  apparently  can 
be  varied  for  specific  requirements.  It  is  one  of  the  new  preser- 
vatives placed  on  the  market. 

Sodium  Silicate. — Made  by  several  companies  in  the  United 
States.  It  does  not  readily  penetrate  wood,  but  has  a  marked  ten- 
dency to  decrease  the  inflammability  of  wood. 

Spirittine. — Manufactured  by  the  Spirittine  Chemical  Com- 


APPENDICES  253 

pany  of  Wilmington,  N.  C.  This  is  a  special  " creosote"  made 
from  coniferous  wood,  and  has  been  used  quite  extensively  in  the 
United  States  with  good  results. 

B.  M.  Preservative. — The^gent  in  this  country  is  Franz 
Workman,  31  Liberty  Street,  New  York  City.  It  is  a  mixture  of 
zinc  chloride  and  normal  aluminum  sulphate,  and  has  been  tested 
experimentally  on  a  large  scale  in  this  country  but  has  not  been 
commercially  practised  to  any  appreciable  extent.  It  is  forced 
into  wood  in  much  the  same  manner  as  in  Burnettizing. 

Water-Gas  Tar  Creosote. — Made  by  a  number  of  companies 
in  the  United  States  but  seldom  sold  under  its  own  name.  Often 
mixed  with  coal-tar  creosote.  Tests  by  the  U.  S.  Forest  Service 
show  it  to  have  considerable  merit  as  a  wood  preservative,  but  not 
as  efficient  for  general  purposes  as  coal-tar  creosote. 

Holz-Helfer.— Handled  by  the  Vaughn  Paint  Co.  of  Cleveland, 
Ohio,  and  made  in  Germany.  The  wood  is  either  painted  with  or 
dipped  in  the  solution.  It  is  a  greenish-brown  liquid  containing 
zinc  chloride,  copper,  and  creosote  with  a  specific  gravity  at  60°  C. 
of  1.113.  From  tests  made  at  the  U.  S.  Forest  Products  Lab- 
oratory it  appears  to  be  much  less  toxic  than  creosote. 

Wood  Creosote. — Made  by  several  companies  in  the  United 
States  but  not  used  extensively.  Tests  by  U.  S.  Forest  Service 
show  it  to  have  considerable  merit  as  a  wood  preservative  and  its 
use  for  this  purpose  will  quite  likely  grow,  especially  for  super- 
ficial treatments.  At  present  it  varies  greatly  in  composition  and 
toxic  properties  and  costs  more  than  coal-tar  creosote. 

Sodium  Fluoride. — Made  by  large  manufacturing  chemists 
in  the  United  States.  Little  known  in  this  country  but  exten- 
sively tested  abroad.  Experiments  by  the  U.  S.  Forest  Products 
Laboratory  indicate  the  possibility  of  using  this  salt  to  decided 
advantage.  Further  tests  are  necessary  before  is  full  value  is 
known.  It  is  impregnated  into  wood  as  in  the  Burnettizing 
process. 

Aczol. — Manufactured  by  J.  Gerlache,  Boulevard  du  Nord, 
68  Brussels,  Belgium.  This  is  a  cuprous-ammonium  salt,  which 
is  not  used  to  any  extent  as  yet  in  the  United  States  but  is  under- 
going experiments  with  the  U.  S.  Forest  Service. 

Sapwood  Antiseptic. — Made  and  patented  by  J.  W.  Long, 
Chicago,  111.  It  is  a  mixture  of  copper  sulphate,  sodium  chloride, 
calcium  sulphate,  zinc  sulphate,  and  iron  sulphate  with  water.  Is 
now  undergoing  test  by  the  U.  S.  Forest  Products  Laboratory  and 


254        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

elsewhere.  Is  claimed  to  prevent  sap  stain  as  well  as  decay. 
Toxic  tests  show  it  to  possess  a  very  low  resistance  to  fungi. 

N.  S.  Special. — Manufactured  by  the  Geo.  W.  Saums  Co, 
Trenton,  N.  J.  It  is  a  yellowish,  oily  liqiud  with  a  strong  varnish 
or  paint  odor.  Tests  made  at  the  U.  S.  Forest  Products 
Laboratory  show  it  to  have  a  low  resistance  to  fungi. 

Imperial  Wood  Preservative. — This  is  a  comparatively  light 
gravity,  greenish-black  oil,  handled  in  St.  Louis,  Mo.,  containing 
a  high  percentage  of  residue  at  315°  C.  It  is  under  test  by  the 
U.  S.  Forest  Service  and  elsewhere,  and  is  giving  results  not  very 
unlike  those  obtained  from  coal-tar  creosote. 

Kreodone. — This  is  a  special  wood-preserving  oil  made  by 
the  Republic  Creosoting  Company  of  Indianapolis,  Ind.,  and  else- 
where and  used  largely  for  preserving  wood  blocks.  It  is  reported 
as  giving  good  service. 

Locustine. — Manufactured  by  W.  H.  Huff,  Beverly,  N.  J. 
It  is  reported  as  being  a  patented  compound  of  nonvolatile  pe- 
troleum products  and  certain  animal  and  marine  oils  and  anti- 
septics, which  can  be  applied  to  wood  either  by  the  brush,  dipping, 
or  impregnation  processes. 

Creoline. — This  is  a  very  light  gravity,  brown  oil  containing 
much  tar  acids  and  water.  In  spite  of  this  it  is  giving  good  results 
in  some  test  pole  lines  set  under  the  supervision  of  the  U.  S. 
Forest  Service  and  the  Bell  Telephone  Company. 


LIST  OF  MANUFACTURERS  OF  ZINC  CHLORIDE  IN  THE 
UNITED  STATES 

General  Chemical  Co.     112  W.  Adams  St.,  Chicago,  111. 
Graselli  Chemical  Co.     Cleveland,  Ohio. 
Sandoval  Zinc  Company.     East  St.  Louis,  111. 

LIST  OF  MANUFACTURERS  OR  DEALERS  OF  CREOSOTE  IN 
THE  UNITED  STATES 

American  Conduit  Company,  East  Chicago,  Ind. 
Armitage  Manufacturing  Company,  Richmond,  Va. 
American  Wood  Preserving  Company,  Chicago,  111. 

Barrett   Manufacturing   Company,    New   York,    Chicago,   and   various 
offices. 

Barnay,  J.  R.,  Seattle,  Wash. 
Betts,  C.  G.,  Spokane,  Wash. 

Burton  Coal  and  Lumber  Company,  Salt  Lake  City,  Utah. 
Carolina  Portland  Cement  Co.,  Atlanta,  Ga. 


APPENDICES 


255 


Creosote  Supply  Co.,  Chalmette,  La. 

Chat  field  Manufacturing  Co.,  Carthage,  Ohio. 

Coal-tar  Products  Company  of  New  York. 

Clintock  &  Irvine  Co.,  Pittsburgh,  Pa. 

Dominion  Tar  and  Chemical  Com^ny,  Sidney,  Nova  Scotia. 

Diem  &  Wing  Paper  Co.,  Cincinnati,  Ohio. 

Denver  Gas  &  Electric  Co.,  Denver,  Colo. 

International  Creosoting  Construction  Co.,  Galveston,  Texas. 

C.  Lembcke  &  Company,  New  York  City. 

J.  F.  Lewis  Manufacturing  Co.,  Chicago,  111. 

National  Analine  &  Chemical  Co.,  New  York  City. 

Nashville  Chemical  Co.,  Nashville,  Tenn. 

Pehlam  Bay  Chemical  Co.,  Mount  Vernon,  N.  Y. 

Pacific  Cresoting  Co.,  Seattle,  Wash. 

Republic  Creosoting  Co.,  Minneapolis,  Minn. 

Semet-Solvay  Company,  Kingsley,  Ala. 

Southern  Roofing  Company,  Atlanta. 

United  Gas  Improving  Co.,  Philadelphia,  Pa. 

Utah  Light  &  Railway  Co.,  Ogden,  Utah. 

Warren  Brothers,  Cambridge,  Mass. 

Western  Electric  Company,  Salt  Lake  City,  Utah. 

Zopher  Mills,  91  Williams  St.,  Brooklyn,  N.  Y. 


LIST  OF  WOOD -PRESERVING  PLANTS  IN  THE  UNITED  STATES 
EASTERN  STATES 


Location  of  plant 

Managing  company 

Year 
built 

No. 
of  re- 
torts 

Diam. 
retorts 
(in.) 

Length 
retorts 
(feet) 

Long  Island  City,  N.  Y. 

Eppinger  &  Russell  Co  

1878 

4 

72 

100 

Rome,  N.  Y  

Federal  Creo.  Co  

1910 

2 

84 

150 

Bound  Brook,  N.  J  

Federal  Creo.  Co  

1909 

1 

84 

150 

Newark,  N.  J. 

American  Creosoting  Co 

1906 

2 

78 

105 

Paterson,  N.  J. 

Federal  Creo   Co 

1909 

1 

84 

150 

Maurer,  N.  Y  

Barber  Asphalt  Pav   Co 

1905 

4 

72 

115 

Port  Reading,  N.  J  
Greenwich,  Pa  

P.  &  R.  R.  R.,  C.  R.  R.  of  N.  J..  . 
Penna.  R.  R  

1912 
1910 

2 
2 

88 
72 

140 
132 

Mt.  Union,  Pa  
Broadford  Jc.,  Pa  
Bradford,  Pa  
Buell,  near  Norfolk,  Va 

Penna.  R.  R  
Pittsburgh  Wd.  Pres.  Co  
Buff.,  Roch.  &  Pgh.  R.  R  
U.  S.  Wood  Pres.  Co  

1909 
1911 
1910 
1907 

1 
1 
1 

2 

72 
84 
75 
78 

132 
132 
95 
150 

Buell,  near  Norfolk,  Va 

Norfolk  Creosoting  Co  

1896 

4 

78 

100 

1 

78 

105 

Norfolk,  Va 

Atlantic  Creo  &  Wood  Preserving 

1905 

1 
1 

84 
78 

125 

62 

Portsmouth,  Va  
Green  Spring,  W.  Va... 

Co. 

Wyckoff  Pipe  &  Creo.  Co  
Balto.  &  Ohio  R.  R  

1901 
1881 
1912 

1 
1 
4 
2 

78 
78 
74 

84 

82 
126 
102 
132 

256        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


SOUTHERN  STATES 


Location  of  plant 

Managing  company 

Year 
built 

No. 
of  re- 
torts 

Diam. 
retorts 
(in.) 

Length 
retorts 
(feet) 

Gainesville,  Fla  

Atlantic  Coast  Line  R.  R  

1912 

2 

74 

138 

Pensacola,  Fla  

Southern  Pav.  Con.  Co  

1912 

1 

72 

90 

Jacksonville,  Fla  

Eppinger  &  Russell  Co  

1909 

3 

84 

130 

Hull  Fla 

1912 

1 

74 

73 

Macon,  Ga  

Co. 
Central  of  Ga.  R.  R.  Co  

1912 

2 

84 

116 

Atlanta,  Ga  

Southern  Wd.  Pres.  Co  

1908 

1 

72 

70 

Ensley,  Ala  

Pioneer  Lum.  &  Creo.  Co  

1911 

1 

74 

76 

Mobile,  Ala  . 

1906 

2 

74 

130 

McAdory,  Ala  
Southport,    near    New 

Tennessee  Coal,  Iron  and  Rail- 
road Co. 
American  Creosote  Wks 

1909 

1 
1 

72 
84 

65 
172 

Orleans,  La. 
New  Orleans,  La    .  .  . 

New  Orleans  Wd   Pr   Co 

1901 

1888 

1 

1 

108 

72 

172 
125 

Slidell,  La  

Southern  Creosoting  Co 

1879 

1 

84 

150 

Shreveport,  La.   . 

Shreveport  Creo   Co 

1902 
1910 

2 
2 

72 
84 

100 
134 

Winnfield,  La  

Louisiana  Creo   Co 

1906 

1 

72 

126 

Bogalusa,  La  

Colonial  Creo   Co 

1 

72 

80 

Grenada,  Miss  

Ayer  &  Lord  Tie  Co 

1912 
1904 

2 

4 

72 
74 

134 
128 

Gulfport,  Miss  

Gulfport  Creo   Co 

1906 

2 

84 

120 

Gautier,  Miss  

W   Pascagoula  Creo   Wks 

1876 

1 

72 

119 

Louisville,  Miss  

American  Creo   Wks        .    . 

1903 
1912 

2 
1 

72 
108 

115 
172 

Argenta,  Ark  

Ayer  &  Lord  Tie  Co 

1907 

4 

74 

132 

Texarkana,  Ark  
Beaumont,  Tex  

Int.  Creo.  &  Con.  Co  
Int.  Creo.  &  Con   Co           .    ... 

1902 
1892 

1 
1 

114 

72 

165 
125 

Denison,  Tex  
Texarkana,  Tex  

Mo.  Kan.  &  Tex.  Ry.  Co.  of  Texas 
Nat.  Lum.  &  Creo   Co  

1897 
1909 
1910 

1 
4 
2 

108 

72 
84 

140 
108 
132 

Houston,  Tex  

Nat.  Lum.  &  Creo.  Co  

1912 

4 

72 

120 

Houston,  Tex  

Tex.  &  N.  O.  R.  R   Co      

1890 

5 

72 

112 

Somerville,  Tex  

A.,  T.  &  S.  F   R.  R  

1906 

5 

74 

132 

Hugo,  Okla  

American  Creo.  Co  

1907 

2 

84 

134 

APPENDICES 


257 


CENTRAL  STATES 


Location  of  plant 

Managing  company 

Year 
built 

No. 
of  re- 
torts 

Diam. 
retorts 
(in.) 

Length 
retorts 
(feet) 

Toledo,  Ohio  

Federal  Creo.  Co.. 

1909 

3 

84 

134 

Toledo,  Ohio  

Jennison-  Wright  Co. 

1910 

2 

72 

130 

Orrville,  Ohio 

Ohio  Wood  Pres   Co 

1912 

1 

84 

I  00 

Cincinnati,  Ohio 

Comp   Wd   Pres   Co 

1909 

1 

72 

76 

Indianapolis,  Ind  
Shirley,  Ind.  . 

Republic  Creo.  Co  

1903 
1905 

1 
2 

74 

84 

130 
134 

Terre  Haute,  Ind  

Indiana  Zinc-Creo.  Co  

1904 

2 

72 

120 

Terre  Haute,  Ind  

Chicago  Creosoting  Co  

1912 

2 

132 

20 

Bloomington,  Ind  .  . 

Indiana  Creosoting  Co 

1907 

1 

84 

134 

Columbus,  Ind  
Evansville,  Ind  

Indianapolis,  Columbia  &  South- 
ern Trac.  Co. 
Indiana  Tie  Co. 

1909 
1907 

1 
2 

72 

72 

45 
110 

Waukegan,  111  
Carbondale,  111  

Chicago  Creosoting  Co  
Aver  &  Lord  Tie  Co. 

1907 

2 
4 

72 
72 

134 
122 

Marion,  111  

American  Creo.  Co  

1902 
1907 

•  4 
2 

74 
84 

132 
134 

Springfield,  111  

American  Creo.  Co  

Madison,  111. 

Kettle  River  Co 

1909 

4 

84 

135 

Galesburg,  111  
Mt.  Vernon,   111  

C.,  B.  &Q.  R.  R  
T.  J.  Moss  Tie  Co  

1907 

5 
1 

74 
74 

132 
132 

Metropolis,  III.  .  , 

Joyce-Watkins  Co. 

1899 
1914 

1 
1 

72 
72 

117 
132 

Joppa,  111  

Indiana  Tie  Co  

1909 

2 

72 

110 

Bay  City,  Mich  

Michigan  Pipe  Co  

1893 

1 

72 

42 

Escanaba,  Mich  

Chi.  &  N.  W.  Ry.  Co  

1903 

3 

72 

112 

Minneapolis,  Minn.  .  .  . 
Sandstone,  Minn 

Republic  Creosoting  Co  
Kettle  River  Co 

1905 
1904 

2 
2 

74 

72 

130 
120 

Brainerd,  Minn  
Springfield,  Mo 

Nor.  Pac.  Ry  
American  Creo   Co 

1907 
1907 

2 
2 

84 
84 

134 
134 

Kansas  City,  Mo 

American  Creo   Co 

1907 

2 

84 

134 

Topeka,  Kansas  

Union  Pacific  R.  R  

1909 

2 

73 

117 

17 


258        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


ROCKY  MOUNTAIN  AND  PACIFIC  STATES 


Location  of  plant 

Managing  company 

Year 
built 

No. 
of  re- 
torts 

Diam. 
retorts 
(in.) 

Length 
retorts 
(feet) 

Somers,  Mont  

Great  Northern  Ry.  Co  

1901 

4 

72 

110 

Paradise,  Mont  

Nor.  Pac.  Ry.  Co  

1907 

2 

84 

134 

Butte,  Mont  
Sheridan   Wyo 

Anaconda  Cop.  Min.  Co  
C     B  &  Q  R  R  Co 

1910 
1899 

1 
2 

72 
74 

43 
132 

Union  Pacific  R   R   Co 

1903 

2 

73 

117 

Kellogg,  Idaho  

Bunker  Hill  and  Sullivan  Mining 

Co 

1908 

1 

84 

10 

Tacoma  Wash 

St  P  &  Tacoma  Lum  Co 

1912 

1 

84 

130 

Yardley  Wash 

Western  Wd  Pres   Co 

1912 

1 

84 

65 

Lowell  Wash 

Puget  Sd  Wd   Pres   Co 

1 
1 

84 
72 

117 

83 

Seattle   Wash 

J   M   Colman  Co    

1895 
1912 

1 

72 

52 

Eagle  Harbor,  Wash.  .  . 

Pacific  Creosoting  Co  

1884 
1906 

3 

8 

75 
73 

120 
125 

Wyeth,  Ore  

Oregon-Washington    R.     R.     and 

1904 

4 

72 

114 

St.  Helens,  Ore  

Nav.  Co. 
St.  Helens  Creo.  Co  

1912 

2 

84 

136 

Latham,  Ore  

Southern  Pac.  R.  R  

1893 

2 

72 

112 

Bulrington  (near  Port- 
land) Ore  

Columbia  Creo.  Co  

1912 

1 

72 

65 

El   Paso  &  S  W  R  R  Co 

19C2 

2 

72 

106 

Albuquerque,  N.  Mex.  . 

A.  T.  &  S.  F.  Ry.  Co  

1908 

2 

74 

132 

Oakland,  Cal  

So.  Pacific  Ry  

1 

72 

108 

Los  Angeles,  Cal  

So.  Pacific  Ry  

1889 
1907 

1 
2 

72 
72 

138 
112 

San  Pedro,  Cal  

S.  P.  L.  A.  &S.  L.  R.  R  

1908 

2 

72 

117 

OPEN-TANK  PLANTS 


Location  of  plant 

Managing  company 

Year 
built 

Lowell,  Mass  

Otis  Allen  &  Son  

1848 

Portsmouth,  N.  H.                 

Otis  Allen  &  Son  

1875 

Ninticoke,  Pa.   .             .            

Del.  Lack.  &  West.  R.R.  Coal  Mining 

1907 

New  Philadelphia,  Pa                

Dept. 
Phila.  and  Reading  Coal  and  Iron  Co.  .  . 

1908 

New  Orleans,  La  

Reeves  Co  

1910 

Keokuk,  Iowa  

U.  S.  Wood  Pres.  Plant  

1908 

Milan,  111  

U.  S.  Wood  Pres.  Plant  

1908 

Stillwater,  Minn  

U.  S.  Wood  Pres.  Plant  

1908 

Fountain  City,  Wis  

U.  S.  Wood  Pres.  Plant  

1908 

Cleveland   Ohio 

City  of  Cleveland 

1909 

Lead,  S   Dak 

1908 

Portland   Ore 

Carbolineum  W   P   Co 

1910 

Lowell,  Wash 

Puget  Sound  W   P   Co 

1895 

Butte,  Mont 

Anaconda  Cop   Min   Co 

1909 

Fresno,  Cal 

San  Joaquin  Light  and  Power  Co 

1910 

San  Miguel,  Cal 

San  Joaquin  Light  and  Power  Co 

1910 

Oakland,  Cal  
Newark,  N.  J  

So.  Pac.  Ry.  Co  

Public  Service  Corporation  

1899 
1906 

APPENDICES 


259 


LIST  OF  "FIREPROOFING"  PLANTS  IN  THE  UNITED  STATES 

New  York,  N.  Y f  Standard  Wood  Treating  Company. 

New  York,  N.  Y Jpjectric  Fireproofing  Company. 


THE  AMOUNT  OF  WOOD  PRESERVATIVES  USED  IN  THE 
UNITED  STATES 

Creosote  and  zinc  chloride  are  by  far  the  preservatives  con- 
sumed in  largest  quantities  in  the  United  States  for  preserving 
timber.  About  3,000,000  gallons  of  other- preservatives  such  as 
crude  oil,  carbolineum,  and  other  varieties  of  preservatives  de- 
rived from  coal-tar  were  used  in  1912.  In  addition,  copper  sul- 
phate, mercuric  chloride,  and  aluminum  sulphate  were  also  used, 
the  exact  amounts  being  unknown.  The  consumption  of  creo- 
sote and  zinc  chloride  for  preserving  wood  is  shown  in  Table  38. 

TABLE  38. — SHE  APPKOXIMATE  AMOUNT  OF  CREOSOTE  AND  ZINC  CHLORIDE 
CONSUMED  IN  THE  UNITED  STATES' 


Years 

Creosote  (gallons) 

Zinc  chloride 
(pounds)  ; 
all  domestic 

Domestic 

Foreign 

Total 

1908 

17,360,000 

38,640,000 

56,000,000 

19,000,000 

1909 

13,862,000 

37,569,000 

51,431,000 

16,215,000 

1910 

18,184,000 

45,082,000 

63,266,000 

16,803,000 

1911 

21,511,000 

51,517,000 

73,027,000 

16,360,000 

1912 

31,136,000 

52,531,000 

83,666,000 

20,752,000 

(Over  100,000,000  gallons  of  cresote  reported  used  in  1913) 

AMOUNT  OF  TIMBER  TREATED  IN  THE  UNITED  STATES 

The  amount  of  timber  treated  annually  in  the  United  States  is 
shown  in  Table  39. 

In  addition  to  the  amount  shown  in  Table  39,  a  considerable 
amount  of  wood  was  treated  with  other  preservatives  such  as 
carbolineum,  crude  oil,  and  various  coal-tar  products  sold  under 
a  variety  of  trade  names,  but  the  exact  amount  of  which  is 
unknown. 


American  Wood  Preservers'  Association  Proceedings,  1913. 


260        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


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APPENDICES  261 

About  4,000,000  feet  of  lumber  are  also  given  a  "  fireproof " 
treatment  each  year. 

*>? 

LIST  OF  COMPANIES  IN  THE  UNITED  STATES  EQUIPPED 
TO  BUILD  WOOD-PRESERVING  PLANTS 

Allis-Chalmers  Co Milwaukee,  Wis. 

Basshor  T.  C.  Co Baltimore,  Md. 

Bovaird  &  Seyfaud  Mfg.  Co Bradford,  Pa. 

Casey  &  Hedges Chattanooga,  Term. 

Chicago  Bridge  &  Iron  Co Chicago,  111. 

Coeur  d'Alene  Iron  Works Wallace,  Idaho. 

Cole,  R.  D Newan,  Ga. 

Erie  Heating  Co Chicago,  111. 

Fairbanks  Morse  Co St.  Paul,  Minn. 

Graves  (Wm.)Tank  Works East  Chicago,  Ind. 

Gravier  Tank  Works Galveston,  Tex. 

Jacobs  (S.)  &  Sons Birmingham,  Ala. 

Lockett  (A.M.)  &  Co New  Orleans,  La. 

Logan  Iron  Works Brooklyn,  N.  Y. 

Manitowoc  Engineering  Works Manitowoc,  Wis. 

Mine-Smelter  Supply  Co Denver,  Colo. 

Mohr  (John)  &  Sons Chicago,  111. 

Moran  Bros Seattle,  Wash. 

Morris  Sherman  Mfg.  Co ,  Chattanooga,  Tenn. 

National  Boiler  &  Sheet  Iron  Works Indianapolis,  Ind. 

Payne  &  Joubert New  Orleans,  La. 

Petroleum  Iron  Works Sharon,  Pa. 

Power  &  Mining  Machinery  Co Milwaukee,  Wis. 

Reeves  Bros.  Co Alliance,  Ohio. 

Struther- Wells  Co Warren,  Pa. 

Union  Iron  Works San  Francisco,  Cal. 

Vogt  (Henry) Louisville,  Ky. 

Williamette  Iron  &  Steel  Works Portland,  Ore. 

Specifications  for  the  Analysis  of  Creosote. — A  number  of  speci- 
fications for  analyzing  creosote  oil  have  been  proposed  and  are  in 
force.  Perhaps  the  best  known  and  the  one  in  most  extended  use 
is  that  adopted  by  the  American  Railway  Engineering  Associa- 
tion, which  reads  as  follows : 

SPECIFICATIONS  FOR  ANALYSIS  OF  CREOSOTE  OIL  APPROVED 
BY  THE  AMERICAN  RAILWAY  ENGINEERING  ASSOCIATION 

1.  The  sample  taken  for  analysis  shall  be  strictly  average  of  the 
whole  bulk  of  oil  to  be  tested.  The  oil  shall  be  completely 


262        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

liquefied  and  well  mixed  before  samples  are  taken.  Whenever 
possible  a  drip  sample  of  not  less  than  2  gallons  shall  be  taken 
commencing  after  the  oil  has  started  to  run  freely.  When  this 
cannot  be  done,  as  for  instance,  in  large  storage  tanks,  samples 
shall  be  taken  from  various  depths  in  the  tank  by  means  of 
a  tube  or  bottle,  the  number  of  samples  depending  on  local 
conditions. 

For  taking  samples  during  the  process  of  treatment  a 
sample  of  the  oil  shall  be  taken  from  the  storage  tank  about  1 
foot  from  the  bottom  of  the  tank  before  the  cylinder  is  filled,  and, 
where  possible,  a  sample  directly  from  the  cylinder  during  the 
process  of  treatment.  For  this  purpose  a  thermometer  well 
may  be  used. 

The  sample  to  be  analyzed  shall  be  thoroughly  liquefied  by 
heating  until  no  crystals  adhere  to  a  glass  stirring  rod,  and  also 
well  shaken,  after  which  one-half  shall  be  taken  for  analysis  and 
the  balance  reserved  as  check  test. 

2.  The  apparatus  for  distilling  the  creosote  shall  consist  of  a 
stoppered  glass  retort  similar  to  that  shown  in  diagram  having 
a  capacity  as  nearly  as  can  be  obtained  of  8  ounces  up  to  the 
bend  of  the  neck  when  the  bottom  of  the  retort  and  the  mouth 
of  the  off-take  are  in  the  same  plane.     A  nitrogen  filled  mercury 
thermometer  of  good  standard  make,  divided  into  full  degrees 
Centigrade,  shall  be  used  in  connection  therewith.     In  order  to 
insure  uniform  results  for  comparative  purposes,  the  length  of 
the  thermometer  bulb  shall  be  one-half  (1/2)  inch;  but  in  no  case 
shall  a  thermometer  with  a  long  bulb  be  used.     The  bulb  of  the 
retort  and  at  least  two  (2)  in.  of  the  neck  shall  be  and  remain 
covered  with  a  shield  of  heavy  asbestos  paper,  shaped  as  shown 
in  diagram,  during  the  entire  process  of  distillation,  so  as  to 
prevent  heat  radiation,  and  between  the  bottom  of  the  retort  and 
the  flame  of  the  lamp  or  burner  two  sheets  of  wire  gauze,  each 
20-mesh  fine,  and  at  least  6  inches  square,  shall  be  placed. 

The  flame  shall  be  protected  against  air  currents.  An  ordi- 
nary tin  can,  from  which  a  portion  of  the  bottom  and  all  of  the  top 
have  been  removed,  placed  on  a  support  attached  to  the  burner,  as 
shown  in  diagram,  will  answer  the  purpose. 

3.  Before  beginning  the  distillation  the  retort  shall  be  care- 
fully weighed  and  exactly    100  grams  of  oil    placed  therein, 
the   same    being   weighed   in   the   retort.     The    thermometer 
shall  be  inserted  in  the  retort  with  the  lower  end  of  the  bulb 


APPENDICES  263 

1/2  inch  from  the  surface  of  the  oil  and  the  condensing  tube 
attached  to  the  retort  by  a  tight  cork  joint.  The  distance  be- 
tween the  bulb  of  the  thermometer  and  the  end  of  the  condensing 
tube  shall  not  be  less  than^O  nor  inore  than  24  inches,  and 
during  the  progress  of  the  distillation  the  thermometer  shall 
remain  in  the  position  originally  placed. 

The  distillate  shall  be  collected  in  weighed  bottles  and  all 
fractions  determined  by  weight.  Reports  shall  be  made  on  the 
following  fractions: 

0  to  170°  C.  235  to  270°  C. 

170  to  200°  C.  270  to  315°  C. 

200  to  210°  C.  315  to  355°  C. 

210  to  235°  C.  Residue  above  355°   C. 

Reports  shall  be  made  on  individual  fractions.  In  making 
such  reports  it  is  to  be  distinctly  understood  that  these  frac- 
tions do  not  necessarily  refer  to  individual  compounds.  In  other 
words,  the  fraction  between  210  and  235°  will  not  neces- 
sarily be  all  naphthalene,  but  will  probably  contain  a  number  of 
other  compounds. 

The  distillation  shall  be  a  continuous  one,  and  should  require 
about  45  minutes. 

When  any  measurable  quantity  of  water  is  present  in  the  oil 
the  distillation  shall  be  stopped,  the  oil  separated  from  the  water 
and  returned  to  the  retort,  when  the  distillation  shall  be  re- 
commenced and  the  previous  readings  discarded.  In  obtaining 
water-free  oil,  it  is  desiiable  to  free  about  300  to  600  c.c.  of  the  oil 
by  using  a  large  retort  and  using  100  grams  of  the  water-free  oil 
for  the  final  distillation.  In  the  final  report  as  to  fractions, 
a  correction  shall  be  made  of  the  amount  of  water  remaining,  so 
that  the  report  may  be  made  on  the  basis  of  dry  oil. 

4.  In  order  to  determine  the  specific  gravity  of  any  oil,  simply 
heat  the  oil  in  a  water  bath  until  it  is  completely  liquid.  A 
glass  stirring  rod  dipped  into  the  liquid  should  show  no  solid 
particle  on  the  rod  when  the  same  is  withdrawn  from  the  oil. 
When  completely  liquid,  it  should  be  stirred  thoroughly  and  the 
hydrometer  cylinder  filled,  which  has  previously  been  warmed. 
Insert  a  specific  gravity  hydrometer  of  good  make,  taking  care 
that  the  hydrometer  does  not  touch  the  sides  or  bottom  of  the 
cylinder  when  the  reading  is  taken.  This  reading  should  prefer- 
ably be  taken  when  the  oil  is  at  38°  C.  (100°  F.),  because 


264        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

at  this  temperature  almost  all  oils  are  completely  fluid. 
Where  contract  requirements  specify  a  specific  gravity  at  a  dif- 
ferent temperature,  such  gravity  is  obtained  by  multiplying 
0.0008  by  the  number  of  degrees  Centigrade,  or  0.00044  by  the 
number  of  degrees  Fahrenheit,  the  oil  is  found  to  be  above  the 
temperature  required  by  the  contract,  and  adding  the  product  to 
the  observed  gravity. 

If  it  is  desired  to  ,make  further  chemical  analysis  for  the 
determination  of  the  low- boiling  tar  acids  and  the  naphthalerfe, 
the  following  method  is  recommended,  tentatively: 

"For  the  determination  of  low-boiling  tar  acids,  the  fractions 
should  be  placed  in  a  separating  funnel,  to  which  should  be  added 
about  30  c.c.  of  the  15  percent  hot  sodium  hydroxide  solution, 
vigorously  shaken,  and  allowed  to  stand  until  the  dissolved 
phenols  separate  out  and  may  be  diawn  off,  after  which  repeat 
with  successive  sodium  hydroxide  solutions  20  c.c.  each  time  until 
no  phenols  are  left  (the  sodium  solution  comes  off  clear).  The 
phenols  so  obtained  should  be  separated  by  the  addition  of  a  25 
percent  sulphuric  acid,  slowly  stirred  in.  When  this1  reaction  is 
complete,  the  phenols  so  obtained  should  be  decanted  and 
weighed/' 

The  Committee  on  Wood  Preservation  of  the  National  Electric 
Light  Association  was  not  entirely  satisfied  with  the  above  speci- 
fications for  analysis  and  drew  up  a  set  of  its  own.1  In  the  opin- 
ion of  this  committee  the  above  specification  does  not  fully  meet 
present  requirements  because  "it  is  generally  admitted  by  chem- 
ists that  the  retort  is  an  antiquated  piece  of  apparatus/'  and  fur- 
thermore the  test  is  not  sufficiently  stringent  to  detect  adultera- 
tions. The  specification  for  analysis  which  this  committee  rec- 
ommended reads  as  follows: 

ANALYSIS  SPECIFICATIONS  (NATIONAL  ELECTRIC  LIGHT 
ASSOCIATION) 

General 

"The  apparatus  employed  in  making  the  distillation  and  other 
tests  required  under  these  specifications  shall  conform  in  general 
to  that  shown  on  drawings  Fig  26  (Fig.  No.  a)  and  Fig.  27  at- 
tached to  and  forming  a  part  of  these  specifications,  except  that 
a  five  percent  (5%)  variation  from  the  dimensions  given  is 

1  Report  of  Committee  on  Preservative  Treatment  of  Poles  and  Cross 
Arms,  National  Electric  Light  Association,  1911. 


APPENDICES 


265 


allowed.  The  distilling  apparatus  must  be  assembled  as  in  draw- 
ing Fig  28.  As  further  defining  the  requirements  in  this  re- 
spect, the  following  description  of  certain  parts  and  manner  of 
assembling  is  given  ^ 

(a)  Flask. — The  flask  required  is  a  Lunge  side  neck  distilling 
flask,  provided  with  a  trap  (Fig.  26),  and  having  a  tubular 
side  neck  thirty  centimeters  (30  cm.)  long  placed  close  to  the 
bulb.  The  flask  must  have  a  capacity  of  three  hundred  cubic 


Distilling  Flask 
(Full  Size) 


upport  for  Flask 
(Half  Size) 


Thermometer 


FIG.  26. 


FIG.  27. 


centimeters  (300  c.c.)  when  filled  to  a  height  equal  to  its  maximum 
horizontal  diameter. 

(6)  Thermometer. — The  thermometer  must  be  made  of  Jena 
glass  and  be  nitrogen  filled  and  graduated  at  intervals  of  one 
millimeter  (1  mm.)  in  single  degrees  Centigrade,  the  scale  reading 
to  plus  four  hundred  degrees  Centigrade  (+  400°  C.). 

(c)  Receivers. — The  glass  receivers  may  be  of  any  convenient 
size  and  shape;  the  flask  shown  on  drawing  No.  114  is,  however, 
recommended. 


266        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


(d)  Shield. — A  shield  ten  centimeters  (10  cm.)    in  diameter 
and  eight  centimeters  (8  cm.)   high,  made  of  asbestos,  must 
be  provided  (Fig.  27). 

(e)  Support  for  Flask. — The  flask  must  rest  on  an  asbestos 
board  one-half  centimeter  (0.5  cm.)  in  thickness  by  fifteen  centi- 
meters (15  cm.)  in  diameter,  a  hole  five  centimeters  (5  cm.)  in 
diameter  being  cut  in  the  center  of  the  board.     The  board  shall 
rest  on  a  ring  stand  (Fig.  27). 

ASSEMBLING  APPARATUS 

The  apparatus  must  be  assembled  as  shown  in  figure  No. 
28.     The  thermometer  passes  through  a  cork  in  the  top  of  the 


FIG.  28. 

flask  and  is  so  placed  that  the  top  of  the  bulb  of  the  thermometer 
is  on  a  line  with  the  bottom  of  the  tubular  outlet.  The  asbestos 
shield  is  placed  around  the  bulb  of  the  flask  and  the  flask  mounted 
on  the  asbestos  board  supported  on  the  ring  stand  as  shown  on 
drawing  Fig.  28. 

Distillation  Test 

Two  hundred  grams  of  the  oil  shall  be  used  in  the  analysis, 
this  amount  being  weighed  on  a  balance  sensitive  to  one  milligram 
(1  mg.),  in  the  following  manner: 


APPENDICES  267 

The  flask  is  first  placed  on  the  pan  of  the  balance  and  weighed, 
and  the  weight  recorded.  Without  lemoving  the  flask,  a  two 
hundred  (200)  gram  weight  is  placed  on  the  opposite  pan  of  the 
balance  and  a  sufficient  quantity  of  the  oil  dropped  into  the 
flask  through  a  long  stem  funnel  to  bring  the  pans  into  equi- 
librium. The  flask  is  then  removed  from  the  balance  and  set  up 
as  in  drawing  Fig.  28.  Care  must  be  taken  that  the  cork 
stopper  carrying  the  thermometer  fits  tightly  into  place.  The 
flask  should  be  heated,  preferably  by  a  Bunsen  or  other  standard 
form  of  gas  burner.  The  distillation  shall  be  continuous  and 
at  such  a  rate  that  two  (2)  drops  of  oil  per  second  (5  c.c.  per 
minute)  leaves  the  end  of  the  tubular  after  the  thermometer 
registers  two  hundred  and  five  degrees  Centigrade  (205°  C.), 
or  after  all  of  the  water  has  been  driven  off.  The  percentage 
weights  of  the  following  fractions  shall  be  recorded: 

To  205°  C. 
To  235°  C. 
To  245°  C. 
To  270°  C. 
To  315°  C. 
To  360°  C. 

DETERMINATION  OF  FREE  CARBON 

The  apparatus  required  is  as  follows  : 

Knorr  Condenser. 

Knorr  Flask. 

C.  S.  &  S.  No.  575  Filter  Papers,  15  cm.  diameter. 

Wire  for  supporting  filter  papers. 

Ten  grams  of  the  oil  should  be  weighed  into  a  small  beaker 
and  digested  with  C.  P.  toluol  on  a  steam  bath.  A  cylindrical 
filter  cup  is  prepared  by  folding  two  of  the  papers  around  a  rod 
about  five-eights  of  an  inch  (5/8")  in  diameter.  The  inner 
paper  should  be  cut  to  fourteen  centimeters  (14  cm.)  diameter. 
Prior  to  using  the  filter  papers,  they  should  have  been  extracted 
with  benzol  to  render  them  fat  free.  The  filter  cup  is  dried  at 
one  hundred  (100)  to  one  hundred  and  ten  (110)  degrees 
Centigrade  and  weighed  in  a  weighing  bottle. 

The  contents  of  the  beaker  are  now  decanted  through  the 
filter  cup,  and  the  beaker  washed  with  hot  toluol,  passing  all 
washings  through  the  cup.  The  filtrate  should  be  passed  through 


268        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  filter  a  second  time,  the  residue  washed  two  or  three  times 
with  hot  C.  P.  benzol  and  transferred  to  the  ex ti  action  ap- 
paratus, in  which  C.  P.  benzol  is  used  as  the  solvent,  which 
solvent  is  vaporized  by  means  of  a  steam  or  water  bath.  The 
extraction  is  continued  until  the  filtrate  is  colorless.  The  filter 
cup  is  then  removed,  dried  and  weighed  in  the  weighing  bottle. 
C.  P.  benzol  followed  by  chloroform  may  be  used  instead  of 
C.  P.  toluol  followed  by  C.  P.  benzol. 

Precautions. — In  removing  filter  paper  from  the  extraction 
apparatus  see  that  no  particles  of  mercury  find  their  way  into  the 
precipitate.  To  prevent  splashing,  the  filter  paper  should  be 
elevated  as  near  to  the  outlet  of  the  condenser  as  possible.  A 
good  precaution  is  to  cover  the  top  of  the  filter  cup  with  a  round 
cap  of  filter  paper. 

Sulphonation  Test 

Ten  cubic  centimeters  (10  c.c.)  of  the  total  distillate  to  three 
hundred  and  fifteen  degrees  Centigrade  (315°  C.)  are  placed 
in  a  flask  and  warmed  with  four  (4)  to  five  (5)  volumes  of  con- 
centrated sulphuric  acid  to  sixty  degrees  Centigrade  (60°  C.)  and 
the  whole  transferred  to  a  graduated  separatory  funnel.  The 
flask  is  rinsed  three  times  with  small  quantities  of  concentrated 
sulphuric  acid  and  the  rinsings  added  to  the  contents  of  the 
funnel,  which  is  then  stoppered  and  shaken,  cautiously  at  first, 
afterward  vigorously,  for  at  least  fifteen  (15)  minutes  and  al- 
lowed to  stand  over  night.  The  acid  is  then  carefully  drawn 
down  into  the  graduated  portion  of  the  funnel  to  within  two 
cubic  centimeters  (2  c.c.)  of  where  the  unsulphonated  residue 
shows.  If  no  unsulphonated  residue  is  visible  the  acid  should 
be  drawn  down  to  two  cubic  centimeters  (2  c.c.).  In  either  case 
the  test  should  be  carried  further  as  follows:  Add  about  twenty 
cubic  centimeters  (20  c.c.)  of  water  and  allow  to  stand  for  1/2 
hour.  Then  draw  off  the  water  as  close  as  possible  without 
drawing  off  any  supernatant  oil  or  emulsion,  and  ten  cubic 
centimeters  (10  c.c.)  of  strong  sulphuric  acid  and  allow  to  stand 
for  from  fifteen  to  twenty  (15  to  20)  minutes.  Any  unsulphonated 
residue  will  now  separate  out  clear  and  give  a  distinct  reading. 
If  under  two- tenths  of  a  cubic  centimeter  (0.2  c.c.)  it  should  be 
drawn  down  into  the  narrow  part  of  the  funnel  to  just  above 
the  stop-cock,  where  it  can  be  estimated  to  one  one-hundredth 
of  a  cubic  centimeter  (0.01  c.c.)  The  volume  of  residue  thus 
obtained  is  calculated  to  the  original  oil." 


APPENDICES  269 

DETERMINATION  OF  TAR  ACIDS 

One  hundred  cubic  centimeters  (100  c.c.)  of  the  total  distillate 
to  three  hundred  and  fifteen  degrees  (315°  C.),  to  which  forty 
cubic  centimeters  (40-e.c.)  of  a  solution  of  sodium  hydroxide  having 
a  specific  gravity  of  one  and  fifteen  hundredths  (1.15)  is  added,  is 
warmed  slightly  and  placed  in  a  separatory  funnel.  The  mixture 
is  vigorously  shaken,  allowed  to  stand  until  the  oil  and  soda  solu- 
tions separate  and  the  soda  solution  containing  most  of  the  tar 
acids  diawn  off.  A  second  and  third  extraction  is  then  made 
in  the  same  manner,  using  thirty  (30)  and  twenty  (20)  cubic  centi- 
meters of  the  soda  solution,  respectively.  The  three  alkaline 
extracts  are  united  in  a  two  hundred  cubic  centimeter  (200  c.c.) 
graduated  cylinder  and  acidified  with  dilute  sulphuric  acid.  The 
mixture  is  then  allowed  to  cool  and  the  volume  of  tar  acids  noted. 
The  results  shown  should  be  calculated  to  the  original  oil. 

COKE  TEST 

In  making  the  coke  determination,  hard  glass  bulbs  are  to  be 
used.  The  test  is  to  be  carried  out  as  follows: 

Warm  the  bulb  slightly  to  drive  off  all  moisture,  cool  in  a 
desiccator  and  weigh.  Again  heat  the  bulb  by  placing  it  momen- 
tarily in  an  open  Bunsen  flame  and  place  the  tubular  side  neck 
underneath  the  surface  of  the  oil  to  be  tested  and  allow  the  bulb 
to  cool  until  sufficient  oil  is  sucked  in  to  fill  the  bulb  about  two- 
thirds  full.  Any  globules  of  oil  sticking  to  the  inside  of  the  tubu- 
lar should  be  drawn  into  the  bulb  by  shaking  or  expelled  by  slight- 
ly heating  it,  and  the  outer  surface  should  be  carefully  wiped  off 
and  the  bulb  re- weighed.  This  procedure  will  give  about  one  gram 
of  oil.  Cut  a  strip  of  thin  asbestos  paper  about  one-quarter  inch 
wide  and  about  1  inch  long,  place  it  around  the  neck  of  the  bulb  and 
catch  the  two  free  ends  close  up  to  the  neck  with  a  pair  of  crucible 
tongs.  The  oil  should  then  be  distilled  off  as  in  making  an  ordi- 
nary oil  distillation,  starting  with  a  very  low  flame  and  conducting 
the  distillation  as  fast  as  can  be  maintained  without  spurting. 
When  oil  ceases  to  come  over,  the  heat  should  be  increased 
until  the  highest  temperature  of  the  Bunsen  flame  is  attained,  the 
whole  bulb  being  heated  red  hot  until  evolution  of  gas  ceases 
and  any  carbon  sticking  to  the  outside  of  the  tubular  is  completely 
burned  off.  The  bulb  should  then  be  cooled  in  a  desiccator  and 
weighed  and  the  percentage  of  coke  residue  calculated  to  watei- 
free  oil. 


270        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

Still"  more  refined  specifications  for  analyzing  creosote  oil, 
especially  as  regards  the  method  of  distillation  and  sulphonation 
residues,  are  those  in  use  by  the  U.  S.  Forest  Service.  In  the 
author's  opinion  these  tests  are  much  more  exact  than  either  of 
the  two  just  given.  They  are,  however,  more  troublesome  and 
hence  expensive  to  make,  but  where  accuracy  is  desired,  their  use 
is  recommended. 

SPECIFICATIONS   FOR  ANALYZING  CREOSOTE   USED   BY   THE 
U.  S.  FOREST  SERVICE 

(Note. — All    temperatures  referred  to  in  the  following  are  on 
the  centigrade  scale.) 

SPECIFIC  GRAVITY  OF  THE  WHOLE  OIL 

"The  perfectly  liquefied  oil  is  poured  into  a  hydrometer  cylinder, 
and,  at  a  temperature  of  60°,  the  specific  gravity  is  read  with 
hydrometer  standardized  against,  water  at  60°. 

The  somewhat  prevalent  method  of  determining  specific 
gravity  with  a  hydrometer  standardized  at  15°  and  then  calculat- 
ing the  results  from  the  temperature  of  the  determination  back 
to  15°  is  roundabout  and  involves  the  expression  of  the  specific 
gravity  of  creosote  in  the  liquid  condition  at  a  temperatuie  at 
which  the  oil  does  not  exist  as  a  liquid.  The  method  is  illogical 
and  open  to  inaccuracies.  With  very  rare  exceptions  creosotes 
are  all  liquid  at  60°,  and  if  the  weight  of  a  unit  volume  of  the  oil 
at  60°  is  compared  with  the  weight  of  a  unit  volume  of  water  at  60°, 
a  true  specific  gravity  is  obtained.  . 

FRACTIONAL  DISTILLATION 

The  Hempel  distilling  flask  of  resistance  glass  is  employed. 
The  empty  flask  is  tared,  250  grams  of  melted,  well-shaken  oil 
introduced,  the  platinum- wire  plug  and  the  glass  beads  put  in 
place,  and  a  second  weight  taken.  The  thermometer  is  then 
inserted  in  the  flask,  so  that  the  first  emergent  reading  is  200°. 
The  flask  is  supported  on  an  asbestos  board  with  a  slightly  ir- 
regular opening  of  very  nearly  the  largest  diameter  of  the  flask. 
A  condensing  tube  is  employed  and  the  fractions  are  collected  in 

1  Circular  206,  United  States  Forest  Service. 


APPENDICES  271 

tared  flasks.  The  distillation  is  run  at  the  rate  of  1  drop  per 
second,  and  fractions  collected  between  the  following  tempera- 
tures: Up  to  170°,  170°-205°,'  205°-225°,  225°-235°,  235°-245°, 
245°-255°,  255°-285°.,  285°-2§5°,  295°-305°,  305°-320°,  and  if 
feasible,  320°-360°. 

The  characters  of  the  fractions  and  their  weights  are  recorded 
and  the  results  plotted  as  a  curve,  in  which  the  ordinates  are  per- 
centages by  weight  and  the  abscissae  temperatures.  . 
When  the  distillation  has  reached  the  225°  point,  an  asbestos- 
board  box  should  be  placed  around  the  distilling  flask,  to  cover 
the  bulb,  but  leave  the  Hempel  column  exposed.  Drafts  upon 
the  distilling  apparatus  must  be  avoided. 

INDEX  OF  REFRACTION 

The  indices  of  refraction  of  the  different  fi  actions  between  235° 
and  305°  are  determined  at  60°  in  a  refractometer  with  light 
compensation.  The  results  are  plotted  with  temperatures  as 
abscissae  and  indices  of  refraction  as  ordinates. 

"Index  of  Refraction.—  The  index  of  refraction  is  the  ratio  between  the 
sines  of  the  angles  of  incidence  and  of  refraction  of  light,  expressed  by  the 
f  .  n  sine  I  n 

lormula  -     =  where  -      means  the  index  of  refraction  referred  to 


sodium  light,  /  equals  the  angle  of  incidence,  and  R  the  angle  of  refraction. 
The  index  of  refraction  varies  with  the  temperature,  but  is  constant  for 
any  given  oil  at  a  stated  temperature.  In  making  measurements  of  the 
index  of  refraction  of  the  different  fractions  of  a  creosote  distillation,  it  was 
necessary  to  make  the  measurements  at  60°.  The  determinations  were 
made  with  an  Abbe  refractometer  provided  with  a  light  compensator.  By 
means  of  this  instrument  the  index  of  refraction  may  be  read  with  great 
accuracy,  and  the  measurement  is  one  of  the  most  exact  which  can  be 
applied  to  such  an  oil. 

Sulphonation  Test.  —  In  contradistinction  to  the  hydrocarbons  of  the 
paraffin  series,  those  of  the  aromatic  series  react  with  concentrated  sulphuric 
acid  with  marked  ease.  The  products  of  this  reaction,  in  which  a  sulpho 
group  or  groups  replace  hydrogen  in  the  aromatic  compound,  are  called 
sulphonic  acids  and  the  process  is  known  as  sulphonation.  For  example, 
the  reaction  with  benzene  would  be  C6H6  +  H2SO4  =  CeHbSOsH  +  H2O. 
The  sulphonic  acifls  are  characterized  by  their  solubility  hi  water.  If  a 
fraction  from  the  distillation  of  a  creosote  oil  be  treated  under  proper  con- 
ditions with  concentrated  sulphuric  acid,  it  will  be  converted  into  a  mixture 
of  sulphonic  acids,  which  will  readily  dissolve  hi  water.  If,  however,  there 
are  paraffin  bodies  present  they  will  not  be  attacked  to  the  same  degree  as 

1  The  following  explanation  of  the  index  of  refraction  and  of  the  sulphona- 
tion test  is  taken  from  U.  S.  Forest  Service  Circular  112: 


272        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

the  aromatic  hydrocarbons,  and  when  the  products  of  the  sulphonation  are 
treated  with  water  the  paraffin  components  will  remain  as  a  residual  oil. 
In  applying  this  test  to  creosote  oils  it  has  been  found  that  the  most 
information  is  obtained  by  using  it  on  the  higher  boiling  fractions." 

Specific  Gravity. — The  specific  gravities  of  the  fractions 
between  235°  and  305°  are  determined  by  means  of  specific- 
gravity  bottles.  These  bottles  are  filled  at  60°  and  the  weights 
referred  to  water  at  the  same  temperature.  The  results  are 
plotted  as  a  curve  in  which  the  ordinates  are  specific  gravities 
at  60°  and  the  abscissae  temperatures. 

Sulphonation  Tests.1 — Ten  cubic  centimeters  of  the  fraction  of 
creosote  to  be  tested  are  measured  into  a  Babcock  milk  bottle. 
To  this  is  added  40  c.c.  of  37  times  normal  acid,  10  c.c.  at  a 
time.  The  bottle  with  its  contents  is  shaken  for  2  minutes  after 
each  addition  of  10  c.c.  of  acid.  After  all  the  acid  has  been 
added  the  bottle  is  kept  at  a  constant  temperature  of  from  98° 
to  100°  C.  for  1  hour,  during  which  time  it  is  shaken  vigoiously 
every  10  minutes.  At  the  end  of  an  hour  the  bottle  is  re- 
moved, cooled,  and  filled  to  the  top  of  the  graduation  with  ordi- 
nary sulphuric  acid,  and  then  whirled  for  5  minutes  in  a  Babcock 
separator.  The  unsulphonated  residue  is  then  read  off  from  the 
graduations.  The  leading  multiplied  by  2  gives  percent  by  vol- 
ume directly.  (Each  graduation  equals  one  two-hundredth  of  a 
cubic  centimeter.) 

In  well-equipped  chemical  laboratories  the  usual  steam-jacket 
ovens,  capable  of  maintaining  a  temperature  of  from  98°  to  100° 
C.,  will  keep  the  reaction  mixture  of  the  sulphuric  acid  and  creo- 
sote at  the  proper  temperature.  It  frequently  happens,  however, 
that  creosotes  are  analyzed  in  a  laboratory  equipped  only  for  that 
purpose,  and  for  such  cases  a  special  steam  bath  or  oven  can  be 
made  by  any  tinsmith  at  small  cost.  It  is  essential  that  the 
chamber  be  of  sufficient  size  to  completely  contain  (under  the 
cover)  the  Babcock  bottle;  otherwise  the  exact  dimensions  of  the 
steam  bath  are  unimportant,  and  any  two  vessels  of  suitable  di- 
mensions, which  are  at  hand  or  can  most  readily  be  obtained,  may 
be  utilized  in  its  construction. 

Tar  Acids. — Fifty  cubic  centimeters  of  the  creosote  under  analy- 
sis are  measured  at  60°  into  a  small  distilling  flask  by  a  pipette. 
The  oil  is  distilled  as  completely  as  possible  without  breaking  the 
distilling  bulb,  and  the  distillate  is  caught  in  a  short-stemmed 

1  U.  S.  Forest  Service  Circular  191. 


APPENDICES  273 

100  c.c.  separating  funnel.  At  the  end  of  the  distillation  25 
c.c.  of  boiling  hot  15  percent  sodium  hydroxide  are  added  to 
the  distillate  and  the  mixture  thoroughly  shaken.  The  alkaline 
extract  is  then  drawn  off  in%  a  100  c.c.  cylinder  and  25  c.c. 
more  of  hot  sodium  hydroxide  added.  After  extracting  with 
this  second  portion  for  5  minutes,  with  frequent  shaking,  the 
solutions  are  allowed  to  separate  and  the  alkaline  extract  added 
to  the  first  portion  in  the  cylinder.  A  third  extraction  is  made 
with  15  c.c.  of  alkali.  The  total  alkaline  extract  is  cooled, 
acidified  with  sulphuric  acid,  thoroughly  shaken,  brought  to  60°, 
and  the  volume  of  supernatant  oil  read  off. 

Water. — After  weighing  the  first  two  fractions  of  a  fractional 
distillation  they  are  united  in  a  small  separatory  funnel  and  any 
water  which  is  present  is  separated  froni  the  oil  and  its  amount 
accurately  determined.  If  particular  accuracy  is  required  in 
the  estimation  of  the  water  it  may  be  done  by  the  Marcusson  xylol 
distillation  method.1" 

METHOD  FOR  DETERMINING  THE  AMOUNT  OF  MOISTURE  IN 
CREOSOTE  AND  CREOSOTED  WOOD 

"The  creosoted  wood,  in  the  form  of  borings,  turnings,  saw- 
dust, or  similar  material,  is  quickly  weighed  and  transferred  to 
the  250  c.c.  Erlenmeyer  flask,  and  75  c.c.  of  water-saturated 
xylol2  added.  The  basin  in  which  the  flask  is  placed  should 
be  two-thirds  full  of  melted  paraffin  or  of  some  heavy  lubricat- 
ing oil  such  as  cylinder  oil.  The  bath  is  heated  and  the  distil- 
lation continued  until  the  distillate  comes  in  clear  drops.  At 
the  end  of  the  distillation  the  condenser  should  be  rinsed  with 
the  stream  from  a  wash  bottle  containing  xylol.  After  it  has 
stood  for  a  short  time,  the  emulsion  of  water  and  xylol  separates, 
giving  two  clear  liquid  layers.  The  mean  of  the  readings  at  the 
top  and  bottom  of  the  meniscus,  between  xylol  and  water,  gives 
the  volume  of  water,  and  the  percentage  of  moisture  in  the 
wood  is  obtained  by  multiplying  the  water  volume  by  4.  There 
are  always  small  globules  of  water  adhering  to  the  sides  of  the 
graduate  in  the  portion  filled  with  xylol.  These  are  readily 

1  Forest  Service  Circular  134,  The  Estimation  of  Moisture  in  Creosoted 
Wood,  A.  L.  Dean. 

2  Water-saturated  xylol  is  readily  prepared  by  heating  a  mixture  of  water 
and  xylol  with  frequent  shakings  and  subsequently  removing  the  water  in  a 
separatory  funnel. 

18 


274        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

scrubbed  down  with  a  piece  of  rubber  tube  on  the  end  of  a  piece 
of  glass  tubing,  which  is  better  for  this  purpose  than  the  rod  com- 
monly used  for  a  "policeman." 

It  is  important  that  the  distillation  be  carried  on  slowly  to 
allow  all  the  water  in  the  wood  to  volatilize.  The  finer  the  wood 
particles,  the  more  rapid  may  be  the  distillation.  If  rather 
coarse  material  is  used,  the  distillation  should  not  run  faster  than  1 
drop  per  second. 

The  apparatus  shown  in  Fig.  29  was  devised  for  making 
large  numbers  of  moisture  estimations  on  creosoted  wood.  The 


FIG.  29. — Apparatus    for    making    several    moisture    determinations    in 

creosoted  wood. 

compartments  of  the  paraffin  bath  are  larger  than  necessary  for 
the  250  c.c.  flasks,  but  the  apparatus  was  designed  so  that  larger 
flasks  might  be  employed  when  considerable  wood  was  to  be  used, 
for  purposes  of  investigation,  to  obtain  very  accurate  results. 

Marcusson's  method  is  well  adapted  to  the  estimation  of  water 
in  creosote  oils.  The  apparatus  used  for  creosoted  wood  is  satis- 
factory for  creosote,  except  that  a  wire  gauze  should  be  sub- 
stitute for  the  paraffin  bath.  The  250  cubic  centimeter  flask 
is  weighed,  50  cubic  centimeters  of  melted,  well-shaken  creosote 
introduced,  and  a  second  weight  taken.  Seventy-five  cubic 
centimeters  of  water-saturated  xylol  are  added  and  the  mixture 
distilled  until  the  water  ceases  to  come  off.  The  percentage  of 
water  is  obtained  by  dividing  the  volume  (cubic  centimeters) 
of  water  in  the  distillate  by  the  weight  (grams)  of  creosote.  The 
results  are  likely  to  run  one  or  two-tenths  of  a  percent  too  low. 


APPENDICES 


275 


THE  DURABILITY  OF  AMERICAN  TIMBERS 

The  durability  of  timber  is  so  exceedingly  variable  that  any 
general  table  is  of  value  solety  in  securing  an  approximate  idea  of 
the  durability  of  one  wood  a&  compared  with  another — and  not 
as  an  index  of  what  the  wood  will  actually  do  under  all  con- 
ditions. For  example,  timber  used  in  the  South  and  exposed  to 
the  weather  will  decay  quicker  than  the  same  timber  placed  under 
similar  conditions  in  the  North;  timber  cut  from  a  given  tree 
may  be  more  durable  than  timber  cut  from  the  same  kind  of 
a  tree  which  grew  next  to  it;  timber  placed  in  one  kind  of  soil 
may  be  far  more  durable  than  the  same  timber  placed  in  another 
soil,  etc.  All  of  these  variations  have  been  discussed  in  the 
preceding  chapters.  Taking  all  of  them  into  consideration  and 
striking  an  average  for  common  practice,  Table  40  has  been 
compiled.  It  naturally  follows  that  these  figures  are  of  chief 
value  in  comparing  the  relative  durability  of  one  kind  of 
untreated  wood  with  another,  and  it  is  believed  that  most  of  them 
are  approximately  correct.  As  more  authentic  data  is  collected, 
it  is  quite  likely  that  changes  in  the  estimated  durability  will  be 
necessary. 

TABLE  40. — THE  ESTIMATED  DURABILITY  OF  UNTREATED  WOOD  IN  CONTACT 

WITH  THE  SOIL 


CZass  A.  —  Very  durable 
woods. 
(These  woods  will  probably 
last  more  than  25  years 
in  contact  with  the  soil) 

Class  B.  —  Durable  woods. 
(These  woods  willprobably 
last  more  than  10  years  but 
less  than  25  years  in  contact 
with  the  soil) 

Class  C.  —  Nondurable  woods. 
(These  woods  will  probably 
last  less  than   10  years  in 
contact  with  the  soil) 

Black  locust 

Chestnut 

Aspen 

Northern  white  cedar 

Southern  white  cedar 

Ash 

Western  red  cedar 

Douglas  fir 

Beech 

Cypress 

Red  gum  (heart) 

Birch 

Mulberry 

White  oaks 

Basswood 

Osage  orange 

Longleaf  pine 

Balsam 

Redwood 

Cottonwood 

Elm 

Red  gum  (sap) 

Blue  gum 

Hemlock 

Red  oaks 

Western  yellow  pine 

Lodgepole  pine 

Loblolly  pine 

Sitka  spruce 

White  spruce 

Sycamore 

Tamarack 

Tupelo 

276        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent. 

Date  issued 

Henry  Aitken,  Darroch, 
Falkirk,  Scotland 

Preserving  timber. 

352,216 

Nov.  9,  1886 

Hugo  Akerhielm,  Chicago, 
111. 

Improvement   in    compositions    for 
preserving  wood. 

185,058 

Dec.  5,   1876 

Augustus,  Allen,  Cass  Co., 
Mich. 

Improved    method    of    preventing 
decay  in  the  timbers  of  bridges, 
buildings,  etc. 

106,647 

Aug.  23,  1870 

Edw.  R.  Andrews,  New 
York,  N.  Y. 

Composition  for  preserving  wood. 

247,234 

Sept.  20,  1881 

W.  C.  Andrews,  New 
York,  N.  Y. 

Vulcanizing  wood. 

430,055 

June  10,  1890 

Philip    F.    Apfel,    Seattle, 
Wash,  and  Ralph  L.  Earn- 
est, Portland,  Ore. 

Protecting  piles  against  worms,  etc. 

883,507 

Mar.  31,  1908 

Oliver  App,  Blue  Mound, 
111. 

Improvement  in  compositions  for 
preserving  wood. 

219,377 

Sept.  9,  1879 

R.  W.  Archer,  Corpus 
Christi,  Tex. 

Improvement  in  processes  for  pre- 
serving wood. 

153,515 

July  28,  1874 

McKenzie  Arnn,  Bristol, 
Va. 

Composition  for  coloring  and  pre- 
serving wood. 

601,767 

Apr.   5,    1898 

McKenzie  Arnn,  Bristol, 
Va. 

Wood  preserving  compound. 

633,778 

Sept.  26,  1890 

Chas.  Arnoudts,  Seattle, 
Wash. 

Composition    for    preserving     piles 
from  teredo,  etc. 

526,552 

Sept.  25,  1894 

Max  Bachert,  New  York, 
N.  Y. 

Apparatus  for  saturating  wood. 

666,915 

Jan.  29,  1901 

Max  Bachert,  New  York, 
N.  Y.  &  D.  W.  O'Neil, 
Newark,  N.  J. 

Preserved  wood  and  process  of  pre- 
paring same. 

602,713 

Apr.  19,  1898 

Thurman     Bailey,     Brid- 
port,  Vt. 

Improvement  in  processes  for  pre- 
paring wood  for  roofing. 

125,251 

Apr.   2,    1872 

Jas.  J.  Barr,  Slidell,  La. 

Automatic  retort-cover. 

857,148 

June  18,  1907 

Jas.  R.  Bate,  Cincinnati, 
Ohio. 

Process  of  preserving  wood. 

522,284 

July  3,  1894. 

Frank  Batter,  Marshfield, 
Ore. 

Apparatus  for  preserving  piles. 

452,513 

May  19,  1891 

J.  H.  Bauer,  Scranton,  Pa. 

Improvement  in  processes  for  treat- 
ing sounding-boards. 

149,426 

Apr.   7,   1874 

S.  Beer,  New  York,  N.  Y. 

Improved  process  for  seasoning  and 
preserving  wood. 

73,565 

Jan.  21,  1868 

APPENDICES 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


277 


Nane  and  address 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Andries  Bevier,  New  York, 
N.  Y. 

Method  bf  preserving  wood. 

%i 

681,032 

Aug.  20,  1901 

V.  W.  Blanchard,  Brid- 
port,  Vt. 

Improved  mode  of  preserving  wood. 

94,704 

Sept.  14,  1869 

Guido  Blenio,  New  York, 
N.  Y. 

Process  for  fireproofing  wood. 

779,761 

Jan  .  10,  1905 

A.  T.  Bleyley,  Conception, 
Mo. 

Improvement  in  processes  for  pre- 
serving burial  cases,  etc. 

175,329 

Mar.  28,  1876 

H.  H.  Blodgett,  Omaha, 
Nebr. 

Wood-preserving  composition 

606,702 

July  5,  1898 

John  B.  Blythe,  Bordeaux, 
France. 

Treating  railway-sleepers. 

313,912 

Mar.  17,  1885 

John  B.  Blythe,  Bordeaux, 
France. 

Apparatus   for  treating,   seasoning 
and  preserving  timber. 

313,913 

Mar.  17,  1885 

John  Borner,  Rahway, 
N.  J. 

Apparatus  for  impregnating  wood. 

703,522 

July  1,  1902 

S.  B.  Boulton,  Cooped 
Hall,  County  of  Hertford, 
England. 

Treating  timber  with  preservative 
fluids. 

247,602 

Sept.  27,  1881 

S.  B.  Boulton,  London, 
Eng. 

Method  of  preserving  timber. 

360,947 

Apr.  12,  1887 

Edmond  Bouvier,  Pensa- 
cola,  Fla. 

Improvement  in  solutions  for  pre- 
serving timber. 

218,659 

Aug.  19,  1879 

Joachim  Brenner,  Gain- 
farn,  Austria-Hungary. 

Process  of  dyeing  wood. 

755,993 

Mar.  29,  1904 

Jas.  P.  Bridge,  Boston, 
Mass. 

Improved  compound  for  preserving 
wood,  leather,  etc. 

86,808 

Feb.   9,    1869 

Robert  E.  Bright,  Gren- 
ada, Miss. 

Apparatus  for  treating  timber. 

887,583 

May  12,  1908 

H.  R.  Brinkerhoff,  Oak- 
park,  111. 

Waterproofed  wood  and  method  of 
making  same. 

686,582 

Nov.  12,  1901 

Albert       Brisbane,    New 
York,  N.  Y. 

Improvement  in  processes  for  treat- 
ing  wood   for   paving   and    other 
purposes 

155,788 

Oct.  13,  1874 

Wm.  Brisley,  and  Wm.  S. 
Finch,  Toronto,  Canada 

Composition  for  preserving  wood. 

359,384 

Mar.  15,  1887 

Chas.  Brown,  Albemarle 
Co.,  Va. 

Improved  process  of  preserving  tim- 
ber from  decay. 

83,758 

Nov.  3,  1868 

278        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Saml.  P.  Brown,  Washing- 
ton, D.  C. 

Improvement  in  preserving  wood. 

115,931 

June  13,  1871 

W.    C.    Bruson,    Chicago, 
111. 

Compound  for  preserving  wood. 

251,346 

Dec.  27,  1881 

Walter    Buehler,     Minne- 
apolis, Minn. 

Preserving  wood. 

899,237 

Sept.  22,  1908 

Walter    Buehler,     Minne- 
apolis, Minn. 

Preserving  wood. 

899,480 

Sept.  22,  1908 

Wm.  W.  Bunnell,  Thomas- 
ville,  Nebr. 

Compound  for  preserving  wood. 

238,341 

Mar.  1,  1881 

Peter    Grant    Burns,    St. 
Louis,  Mo. 

Wood-preserving  apparatus. 

864,092 

Aug.  20,  1907 

Rudolph    G.    Burstenbin- 
der,  Hamburg,  Germany 

Preservation  of  wood. 

266,092 

Oct.  17,  1882 

Jas.    J.    Byers,    Gulfport, 
Miss. 

Wood      saturating      and      coating 
apparatus. 

858,950 

July  2,    1907 

Saml.  Cabot,  Jr.,  Boston, 
Mass. 

Improvement  in  processes  for  pre- 
serving wood. 

184,141 

Nov.  7,  1876 

Saml     Cabot,     Brookline, 
Mass. 

Compound  for  bleaching  and  pre- 
serving wood. 

515,191 

Feb.  20,  1894 

Jas.   Calkins,   New  York, 
N.  Y. 

Improvement  in  preserving  wood. 

78,514 

June  2,  1868 

Jos.   P.   Card,   St.  Louis, 
Mo. 

Preserving  wood. 

254,274 

Feb.  28,  1882 

Jos.    P.    Card,    St.   Louis, 
Mo. 

Process  of  preserving  wood. 

317,440 

May  5,  1885 

J.  P.  Card,  Chicago,  111. 

Solution  for  preserving  wood. 

419,582 

Jan.  14,  1890 

Jos.  B.  Card,  Chicago,  111. 

Method  of  preserving  wood. 

815,404 

Mar.  20,  1906 

C.  S.  Chamberlain,  Oak- 
land, Cal. 

Wood-preserving  apparatus. 

621,774 

Mar.  21,  1899 

Octave   Chanute,    Kansas 
City,  Mo. 

Preserving  timbered  structures. 

430,068 

June  10,  1890 

Octave  Chanute,  Chicago, 
111. 

Process  of  preserving  wood. 

688,932 

Dec.  17,  1901 

S.  B.  Chapman,  Abbeville, 
Ga. 

Solution  for  preserving  lumber. 

764,913 

July  12,  1904 

APPENDICES  279 

List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Sydney  B.  Chapman,  Sky- 
land,  N.  C. 

Treated  wbod  and  process  of  pro- 
ducing the  f  line. 

839,55 

Dec.  25,1906 

Emile  Chevigny 

Composition  of  matter  for  painting 
and  preserving  wood. 

824,794 

July    3,  1906 

William       B.       Chisholm 
Charleston,  S.  C. 

Preservation  of  wood. 

802,680 

Oct.  24,  1905 

Chas.  E.  Clarke,  Geo. 
Hadley,  and  J.  C.  Clif- 
ford, Buffalo,  N.  Y. 

Improved  mode  of  preserving  wood. 

67,104 

July  23,  1867 

E.  W.  Clark,  Hartford, 
Conn. 

Improved   solution  for   the   treat- 
ment of  wood. 

94,869 

Sept.  14,  1869 

Seth  L.  Cole,  Brooklyn, 
N.  Y. 

Improvement  in  preserving  wood. 

124,419 

Mar.  12,  1872 

Seth  L.  Cole,  Brooklyn, 
N.  Y. 

Improvement  in  processes  of  pre- 
serving wood. 

124,420 

Mar.  12,  1872 

Edw.  Z.  Collings,  Camden, 
N.  J. 

Apparatus  for  preserving  wood. 

310,880 

Jan.  20,  1885 

Edw.  Z.  Collings,  Camden, 
N.  J. 

Method  of  preserving  wood. 

317,730 

May  12,  1885 

Jos.    H    Connelly,    Alle- 
gheny, Pa. 

Preserved  wood. 

243,062 

June  21,  1881 

Silas  Constant,  Peekskill, 
N.    Y.  and  John  Smith, 
Brooklyn,  N.  Y. 

Improvement  in  seasoning  and  pre- 
serving wood. 

65,545 

Mar.  17,  1867 

Silas  Constant,  Peekskill, 
and  John  Smith,  Brook- 
lyn, N.  Y. 

Improvement  in  seasoning  and  pre- 
serving wood. 

116,274 

June  27,  1871 

Geo.  C.  Cowles,  Bay  Mills, 
Mich. 

Undressed  lumber  and  process  of 
preserving  same. 

746,678 

Dec.  15,  1903 

E.  L.  Cowling,  Boston, 
Mass. 

Improvement  in  preserving  wood. 

84,733 

Dec.  8,  1868 

C.  M.  Cresson,  Philadel- 
phia, Pa. 

Improvement  in  preserving  wood. 

79,554 

July  7,   1868 

C.  M.  Cresson,  Philadel- 
phia, Pa. 

Improvement  in  seasoning  and  pre- 
serving wood. 

109,872 

Dec.  6,  1870 

C.  M.  Cresson,  Philadel- 
phia, Pa. 

Improvement  in  seasoning  and  pre- 
serving wood. 

109,873 

Dec.  6,   1870 

Wm.  Cross,  Brisbane, 
Queensland. 

Method  of  preserving  timber. 

643,762 

Feb.  20,  1900 

280        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

W.  G.  Curtis,  and  J.  D. 
Isaacs,  San  Francisco, 
Cal. 

Process  of  preserving  timber. 

545,222 

Aug.  27,  1895 

W.  G.  Curtis,  and  J.  D. 
Isaacs,  San  Francisco, 
Cal. 

Process   of  preserving  wood. 

11,515 

Dec.  3,   1895 

A.  R.  Davis,  Cambridge, 
Mass. 

Improved  process  of  treating  wood 
for  covering  walls. 

74,056 

Feb.   4,    1868 

Edw.  Davis,  Redondo, 
Cal. 

Pliable-flange  pile-casing. 

464,960 

Dec.  15,  1891 

J.  C.  Day,  Hackettstown, 
N.  J. 

Improvement  in  seasoning  and  pre- 
serving wood. 

100,380 

Mar.  1,  1870 

J.  A.  Deghuee,  New  York, 
N.  Y. 

Method  of  preserving  and  water- 
proofing wood. 

802,739 

Oct.  24,  1905 

E.  J.  De  Smedt,  New 
York,  N.  Y. 

Improved     composition     for    pre- 
serving timber  and  wood. 

100,608 

Mar.  8,  1870 

B.  H.  Detwiler  and 
S.  G.  Van  Gilder,  Wil- 
liamsport  Pa. 

Improvement  in  preserving  woods. 

111,045 

Jan.  17,  1871 

Fred  Dixon,  London,  Eng. 

Improvement  in  processes  for  treat- 
ing wood. 

181,651 

Aug.  29,1876 

B.  V.  B.  Dixon  and  J.  P. 
Card,  St.  Louis,  Mo. 

Preserving  wood. 

239,033 

Mar.  22,  1881 

John  Dolbeer,  San  Fran- 
cisco, Cal. 

Apparatus  for  steaming  piles. 

333,204 

Dec.  29,  1885 

H.  C.  Dorr,  San  Francisco, 
Cal. 

Compound  for  preserving  wood. 

293,955 

Feb.  19,  1884 

C.  J.  Doyle,  Philadelphia, 
Pa. 

Apparatus  for  preserving  wood. 

645,793 

Mar.  20,  1900 

J.  A.  Draper,  Shaftsbury, 
Vt. 

Improvement    in    compounds    for 
preserving  wood. 

152,620 

June  30,  1874 

Wm.  Dripps,  Coatesville, 
Pa. 

Improved  process  of  restoring  and 
preserving  decaying  railroad  ties. 

96,405 

Nov.  2,  1869 

P.  H.  Dudley,  New  York, 
N.  Y. 

Apparatus  for  impregnating  wood. 

381,682 

Apr.  24,  1888 

P.  H.  Dudley,  New  York, 
N.  Y. 

Preserving  railway-ties. 

406,566 

July  9,  1889 

Firmin  Dufouric,  New 
York,  N.  Y. 

Improvement  in  processes  for  pre- 
serving wood. 

150,841 

May,  12  1874 

APPENDICES 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


281 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

P.  F.  Dundon,  San  Fran- 
cisco, Cal. 

Timber-treating  process. 

%i 

753,052 

Feb.  23,  1904 

Chas.     J.     Eames,     New 
York,  N.  Y. 

Improvement  in  processes  for  pre- 
serving wood. 

134,133 

Dec.  24,  1872 

Edw.  Earle,  Savannah,  Ga. 

Improvement  in  the  mode  of  pre- 
serving timber. 

934 

Sept.  20,  1838 

H.   F.   Eckert,   San  Fran- 
cisco, Cal. 

Apparatus  for  preserving  timber. 

509,724 

Nov.  28,  1893 

H.  L.  Eddy,  Geneva,  N.  Y. 

Improved    method    of    preserving 
wood. 

53,217 

Mar.  13,  1866 

W.  E.  Everette,  Tacoma, 
Wash. 

Method  of  preserving  wood. 

801,859 

Oct.  17,  1905 

L.    S.    Fales,    Monmouth 
Junction,  N.  J. 

Improvement    in    compounds    for 
preserving  wood. 

142,453 

Sept.  2,  1873 

H.  W.  Fawcett,  Titusville, 
Pa.   and    Thomson    Mc- 
Gowan,  Meredith,  Pa. 

Improvement  in  preserving  wood. 

123,009 

Jan.  23,  1872 

J.    S.    George,    Ferndale, 
Wash. 

Injecting  apparatus. 

765,312 

July  19,  1904 

Jos.  L.  Ferrell,  Philadelphia, 
Pa. 

Method  of  and  apparatus  for  fire- 
proofing  wood,  etc. 

620,114 

Feb.  28,  1899 

Jos.  L.  Ferreil,  Philadelphia, 
Pa. 

Process  of  impregnating  wood. 

694,956 

Mar.  11,  1902 

Jos.  L.  Ferrell,  Philadelphia, 
Pa. 

Process  of  impregnating  wood  with 
fireproofing  preservatives,  etc. 

695,450 

Mar.  18,  1902 

Jos.  L.  Ferrell, 
Philadelphia,  Pa. 

Fireproofed  wood  and   method   of 
of  making  same. 

695,678 

Mar.  18,  1902 

Jos.  L.  Ferrell, 
Philadelphia,  Pa. 

Fireproofing  compound  and  method 
of  making  same. 

695,679 

Mar.  18,  1902 

Jos.  L.  Ferrell, 
Philadelphia,  Pa. 

Apparatus  for  impregnating  wood. 

716,400 

Dec.  23,  1902 

Jos.  L.  Ferrell, 
Philadelphia,  Pa. 

Apparatus  for  impregnating  wood. 

716,401 

Dec.  23,  1902 

Jos.  L.  Ferrell, 
Philadelphia,  Pa. 

Apparatus  for  impregnating  wood. 

727,928 

May  12,  1903 

Jos.  L.  Ferrell, 
Philadelphia,  Pa. 

Fireproof  wood,  etc.,  and  the  art  of 
making  same. 

728,452 

May  19,  1903 

282        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Jos.  L.  Ferrell, 
Philadelphia,  Pa. 

Process  of  fireproofing  wood. 

767,514 

Aug.  16,  1904 

Lewis  Feuchtwanger, 
New  York,  N.  Y. 

Improvement  in  preserving  wood. 

123,467 

Feb.  6,   1872 

J.  W.  Fielder, 
Princeton,  N.  J. 

Improvement  in  apparatus  for  pre- 
serving   wood    by    the    Robbins 
Process. 

115,946 

June  13,  1871 

Henry  Flad, 
St.  Louis,  Mo. 

Method  of  seasoning  wood. 

231,783 

Aug.  31,  1880 

Henry  Flad, 
St.  Louis,  Mo. 

Process  of  preserving  wood. 

231,784 

Aug.  31,  1880 

Henry  Flad, 
St.  Louis,  Mo. 

Apparatus    for    the    treatment    of 
timber  for  preserving  it. 

253,361 

Feb.  7,  1882 

Webster  Flockton, 
Bermondsey,  Eng. 

Inprovement    in    metallic  solutions 
for  the  preservation  of  timber. 

130 

Feb.  16,  1837 

H.  P.  Folsom,  and  Howard 
Jones,    Circleville,   Ohio. 

Sterilized  erected  pole. 

837,820 

Dec.  4,  1906 

Henry    Page   Folsom  and 
Howard  Jones, 
Circleville,  Ohio. 

Sterilizing    and    preserving    posts 
and  poles. 

894,619 

July  28,  1908 

B.  S.  Foreman, 
Morrison,  111. 

Improvement   in  preserving  wood, 
railroad  ties,  etc. 

43,191 

June  21,  1864 

B.  S.  Foreman, 

Improvement  in  preserving  wood, 
railroad  ties,  etc. 

4,360 

May  2,  1871 

E.  M.  Fowler, 
New  York,  N.  Y. 

Improvement  in  preserving  blocks 
of  wood. 

112,136 

Feb.  28,  1871 

J.  D.  Francks, 
Hanover,  Germany. 

Process  for  preserving  wood. 

231,419 

Aug.  24,  1880 

Chas.  S.  Friedman, 
Philadelphia,  Pa. 

Method  of  creosoting  wood. 

693,697 

Feb.  18,  1902 

Wm.  T.  Garratt, 
San    Francisco,    Cal.  and 
S.  J.  Lynch, 
Santa  Cruz,  Cal. 

Improvement  in  protecting  wooden 
piles. 

215,600 

May  20,  1879 

Louis  Cathman, 
Washington,  D.  C. 

Drying  apparatus. 

766,340 

Aug.  2,  1904 

Jas.  H.  Catling, 
Murfreesborough,  N.  C. 

Improvement  in  treating  the  timber 
of  old  field  pines. 

113,158 

Mar.  28,  1871 

APPENDICES  283 

List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

J.  W.  Geibel, 
Loysburg,  Pa. 

Process  of  removing  sap,  etc.,  from 
.wood. 

825,819 

July  10,  1906 

Joseph  F.  Geisler, 
New  York,  N.  Y. 

Fireproofing  and  preserving  wood. 

560,614 

May  19,  1896 

Jos.  F.  Geisler, 
New  York,  N.  Y. 

Process  of  fireproofing  and  preserv- 
ing wood. 

675,826 

June  4,  1901 

Jos.  F.  Geisler, 
New  York,  N.  Y. 

Process  of  fireproofing  wood. 

679,739 

Aug.  6,  1901 

J.  S.  George, 
Newport,  Cre. 

Method  of  preserving  timber. 

533,587 

Feb.  5,  1895 

P.  H.  Gerhard, 
Austin,  Tex. 

Apparatus  for  treating  timber. 

794,605 

July  11,  1905 

John  Knowles  and 
Robert  Gilbert, 
London,  Eng. 

Method  of  preserving  timber  and 
other  vegetable  products. 

391 

Sept.  21,  1837 

C.  C.  &  G.  E.  Gilman, 
Eldora,  Iowa. 

Fireproofing  building  materials. 

560,580 

May  19,  1896 

J.  T.  Gilmer, 
Pensacola,  Fla. 

Sap  and  gum  extractor. 

858,380 

July  2,  1907 

J.  L.  Gilmore, 
Minneapolis,  Minn. 

Apparatus  for  creosoting  the  ends 
of  poles. 

797,275 

Aug.  15,  1905 

Edw.  Gold, 
Vancouver,  Can. 

Method  of  protecting  piles. 

686,282 

Nov.  12,  1901 

A.  J.  Goodwin, 
New  Smyrna,  Fla. 

Impregnating     wood,     etc.,     with 
copper. 

414,111 

Oct.  29,  1889 

Geo.  Wm.  Gordon, 
Philadelphia,  Pa. 

Process  of  preserving  wood. 

751,981 

Feb.  9,  1904 

Aug.  Gotthilf, 
New  York,  N.  Y. 

Improvement  in  the  method  of  pro- 
tecting timber  from  destruction  by 
worms,  dry  rot  or  other  processes 
of  spontaneous  decay. 

232 

June  14,  1837 

Wm.  D.  Grimshaw, 
New  York,  N.  Y. 

Improvement  in  processes  and  ap- 
paratus for  preserving  and  curing 
wood. 

218,624 

Aug.  19,  1879 

Gustaf  Grondal, 
Djursholm,  Sweden. 

Channel-furnace  for  treating  wood. 

245,162 

Oct.  31,  1905 

Hugo  Gronwald, 
Berlin,  Germany. 

Process  of  preserving  cork. 

273,645 

Sept.  11,  1906 

284        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Hugo  Gronwald, 
Berlin,  Germany. 

Process  of  preserving  cork. 

830,831 

Sept.  11,  1906 

Tomaso  Guissani, 
Milan,  Italy. 

Process  of  preserving  wood. 

707,224 

Aug.  19,  1902 

Tomaso  Guissani, 
Milan,  Italy. 

Apparatus  for  impregnating  wood. 

713,630 

Nov.  13,  1902 

Stuart  Gwynn, 
New  York,  N.  Y. 

Improved    process    of    saturating 
wood,     cloth,     paper,     etc.,    with 
paraffine. 

52,788 

Feb.  20,  1866 

Erwin  Hagen, 
St.  Louis,  Mo. 

Preserving  wood. 

246,762 

Sept.  6,  1881 

Francis  Hall, 
Tacoma,  Wash. 

Method  of  preserving  wood. 

506,493 

Get.  10,  1893 

Wm.  A.  Hall, 
New  York,  N.  Y. 

Art    of    coloring    and    fireproofing 
wood. 

961,123 

June  14,  1910 

Alex,  Hamar, 
Hungary,  Austria. 

Improvement  in  preserving   wood 
from  decay. 

48,636 

July  4,   1865 

Alex,  Hamar, 
Hungary,  Austria. 

Improvement  in  preserving  timber. 

51,528 

Dec.  12,  1865 

Louis  Hanson, 
Wilmington,  N.  C. 

Apparatus  for  preserving  and  creo- 
soting  wood. 

722,505 

Mar.  10,  1903 

Ludvig  Hansen  and 
Andrew  Smith, 
Wilmington,  N.  C. 

Apparatus  for  creosoting  wood. 

316,961 

May  5,  1885 

Ludvig  Hansen  and 
Andrew  Smith, 
Wilmington,  N.  C. 

Process  for  preserving  wood. 

317,129 

May  5,  1885 

Ludvig  Hansen  and 
Andrew  Smith, 
Wilmington,  N.  C. 

Wood-preserving  apparatus. 

322,819 

July  21,  1885 

Thos.  Hanvey, 
Lancaster,  N.  Y. 

Improvement    in     preparing     and 
preserving  wood. 

62,956 

Mar.  19,  1867 

Smith  T.  Harding, 
Morrison,  111. 

Improved   compound   for   preserv- 
ing wood. 

68,069 

Aug.  27,  1867 

Louis  Harmyer, 
Cincinnati,  Ohio. 

Improved  composition  for  preserv- 
ing wood,  metal,  canvas,  etc. 

73,246 

Jan.  14,  1868 

S.  E.  Haskin, 
Avoca,  N.  Y. 

Method  of  vulcanizing  wood. 

399,196 

Mar.  5,  1889 

APPENDICES  285 

List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent                        N°"  °f 
|  patent 

Date  issued 

S.  E.  Haskin, 
Avoca,  N.  Y. 

Process  of  'and  apparatus  for  vul- 
_canizing  w<KJji. 

488,967 

Dec.  27,  1892 

Fritz  Hasselmann, 
Rapfelburg,  Germany. 

Method  of  impregnating  wood. 

580,488 

April  13,  1897 

Fritz  Hasselmann, 
Munich-Nymphenburg, 
Ger. 

Method  of  impregnating  wood. 

626,538 

June  6,   1899 

Hermann  Haupt, 
Philadelphia,  Pa. 

Improvement  in  drying,  preserving, 
and  coloring  wood  or  other  fibrous 
material. 

99,186 

Jan.  25,  1870 

Robt.  T.  Havens, 
Wilmington,  C  hio. 

Improved    process    for    preparing 
wood  for  boots  and  shoes. 

54,339 

May  1,  1866 

Joshua  R.  Hayes, 
Washington,  D.  C. 

Improvement  in  preserving  wood. 

107,904 

Oct.  4,  1870 

Ira  Hayford, 
Boston,  Mass. 

Improvement   in   the    process  and 
apparatus  for  treating  wood. 

101,012 

Mar.  22,  1870 

Ira  Hayford, 
Boston,   Mass. 

Improvement  in  processes  and  ap- 
paratus for  treating  wood. 

127,482 

June  4,  1872 

Ira  Hayford, 
Boston,  Mass. 

Improvement    in    apparatus    and 
processes  for  preserving  wood. 

194,773 

Sept.  4,  1877 

Wm.  Hayman, 
Taunton,  Mass. 

Improvement  in  compositions  for 
preserving  wood. 

110,652 

Jan.  3,   1871 

Theo.  Wm.  Heinemann, 
New  York,  N.  Y. 

Improved    mode  of  purifying,  sea- 
soning, and  preserving  wood. 

76,757 

Apr.  14,  1868 

Theo.  Wm.  Heinemann, 
New  York,  N.  Y. 

Improved  method  of  seasoning  and 
preserving  wood. 

94,204 

Aug.  17,  1869 

T.  W.  Heinemann, 
New  York,  N.  Y. 

Improved   process    and    apparatus 
for  preserving  wood. 

95,474 

Oct.  5,  1869 

Hubert,  Higgins, 
Cambridge,  Eng. 

Apparatus    for    impregnating    and 
seasoning  wood. 

695,152 

Mar.  11,  1902 

Arthur  Holmes, 
Cortland,  N.  Y. 

Improvement  in  preserving  wood 
from  decay. 

62,334 

Feb.  26,  1876 

Ira  Holmes, 
Moscow,  N.  Y. 

Improvement    in    compounds    for 
preserving  wood. 

124,358 

Mar.  5,  1872 

H.  L.  Houghton, 
Morrison,  111. 

Improved  composition  for  harden- 
ing and  preserving  wood. 

65,674 

June  11,  1867 

Chas.  Howard, 
New  York,  N.  Y. 

Process  of  and  apparatus  for  satu- 
rating wood. 

557,271 

Mar.  31,  1896 

286        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Chas.  Howard, 
New  York,  N.  Y. 

Process  for  preserving  wood. 

899,400 

Sept.  22,  1908 

Wm.  Howe, 
Seattle,  Wash. 

Pile-protector. 

900,929 

Oct.  13,  1908 

Frank  A.  Howig, 
San  Francisco,  Cal. 

Improvement     in     production     of 
wooden  bottle-stoppers  and  bungs. 

197,220 

Nov.  20,  1877 

Pierre  Hugon, 
Paris,  France. 

Improvement  in  apparatus  for  car- 
bonizing wood. 

48,882 

July  18,  1865 

D.  W.  Hunt, 
San  Francisco.Cal. 

Improved   machine    for   kyanizing 
wood. 

91,848 

June  22,  1869 

David  W.  Hunt, 
San  Francisco,  Cal. 

Improvement  in  machines  for  kyan- 
izing wood. 

6,848 

Jan.  11,  1876 

John  Huntington, 
Cleveland,  Ohio. 

Improvement  in  devices  for  impreg- 
nating timber  with  antiseptic  fluid. 

171,135 

Dec.  14,  1875 

John  Huntington, 
Cleveland,  Ohio. 

Improvement  in  devices  for  impreg- 
nating    timber     with     antiseptic 
fluids. 

171,136 

Dec.  14,  1875 

Warren  Iddings, 
Warren  Ohio. 

Preserving  and  hardening  wood. 

398,619 

Feb.  26,  18S9 

B.  A.  Jeager, 
Bower's  Station,  Pa. 

Improved  compound  for  preserving 
wood. 

81,172 

Aug.  18,  1868 

Paul  Jaeger, 
Esslingen,  Germany. 

Method  of  and  apparatus  for  im- 
pregnating and  dyeing  wood. 

578,516 

Mar.  9,  1897 

B.  H.  Jenks, 
Bridesburg,  Pa. 

Improved  process  for  coloring  wood. 

55,110 

May  29,  1866 

B.  H.  Jenks, 
Bridesburg,  Pa. 

Improved  mode  of  treating  wood 
for  the   manufacture  of   carding- 
engines. 

55,111 

May  29,  1866 

B.  H.  Jenks, 
Bridesburg,  Pa. 

Improved     process     of     seasoning 
wood. 

58,425 

Oct.  2,   1866 

Joseph  Jones, 
New  Orleans,  La. 

Improvement  in  preserving  wood. 

118,245 

Aug.  18,  1871 

Thos.  Jones, 
Calstock,  Eng. 

Improvement  in  processes  for  pre- 
serving wood. 

155,191 

Sept.  22,  1874 

Wm.  H.  Jones, 
Rochester,  N.  Y. 

Improvement  in  processes  of  pre- 
serving wood. 

132,584 

Oct.  29,  1872 

APPENDICES 
Iff  List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


287 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Chas.  Karmrodt  and 
Nicholas  Thilmany, 
Bonn,  Prussia. 

Improvement  in  preserving  wood. 

_              1* 

132,584 

Mar.  30,  1869 

Carl  Kleinschmidt, 
Seattle,  Wash. 

Wood-preserving  compound. 

697,632 

Apr.  15,  1902 

Ernst  Koepfer, 
Vienna,  Austria-Hungary. 

Apparatus  for  impregnating  wood. 

910,546 

'Jan.'26,r1909 

Franz  L.  Konrad, 
Munster,  Germany. 

Method  of  fireproofing  wood. 

629,861 

Aug.'l,  1899 

H.  E.  Kreuter, 
Dallas,  Tex. 

Apparatus  for  treating  timber,  rail- 
way ties,  etc. 

249,953 

Nov.  22,  1881 

Rudolph  Kroll, 
Spearfish,  So.  Dak. 

Wood    preservation    by    means    of 
borings  in  timber  to  permit  the 
entrance  of  air. 

727,975 

May  12,  1903 

George  Kron, 
Copenhagen,  Denmark. 

Method    of    producing    liquid-tight 
joints  for  impregnating  wood. 

256,456 

April  19,  1905 

Berthold  Kuckuck, 
Wannsee  near  Berlin,  Ger. 

Apparatus  for  impregnating  wood 
or  other  substances. 

866,487 

Sept.  17,  1907 

John  Howard  Kyan, 
Cheltenham,  Eng. 

Improved  mode  of  preserving  tim- 
ber   and     other    vegetable    sub- 
stances from  decay. 

800 

June  23,  1838 

Sylvester  W.  Labrot, 
New  Orleans,  La. 

Process  of  preserving  wood. 

862,488 

Aug.  6,  1907 

Jas.  Guy  La  Fonte, 
Indianapolis,  Ind. 

Improvement  in  treatment  of  wood 
for  corset  stays,  etc. 

201,022 

Mar.  5,  1878 

Fred.  E.  Lampert, 
San  Francisco,  Cal. 

Coating  for  piles. 

454,744 

June  23,  1891 

C.  S.  Lawrence, 
Plainfield,  Wis. 

Wood-preserving  compound. 

682,363 

Sept.  10,  1901 

Fred.  Lear, 
St.  Louis,  Mo. 

Improvement  in  coloring  and  pre- 
serving wood. 

109,027 

Nov.  8,  1870 

Fred.  Lear, 
St.  Louis,  Mo. 

Improvement  in  preserving,  color- 
ing, and  seasoning  wood. 

116,969 

July  11,   1871 

Georg   Friedrich  Lebioda, 
Boulogne-sur-Seine, 
France. 

Apparatus  for  dyeing  and  impreg- 
nating wood. 

609,442 

Aug.  23,  1898 

Georg   Friedrich  Lebioda, 
Boulogne-sur-Seine, 
France. 

Apparatus  for  impregnating  wood. 

644,252 

Feb.  27,  1900 

288        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Georg  Friedrich  Lebioda, 
Boulogne-sur-Seine, 
France. 

Apparatus  for  impregnating  wood. 

655,788 

Aug.  14,  1900 

Georg  Friedrich  Lebioda, 
Boulogne-sur-Seine, 
France. 

Apparatus  for  impregnating  wood. 

689,317 

Dec.  17,  1901 

Georg  Friedrich  Lebioda, 
Boulogne-sur-Seine, 
France. 

Process  of  obtaining  impregnated 
wood. 

729,362 

May  26,  1903 

Chas.  T.  Lee, 
Boston,  Mass. 

Process  of  preserving  wood. 

419,858 

Jan.  21,  1890 

Louis  L.  Le  Franc, 
Bosc-le-Hard,  France. 

Manufacture  of  wooden  stoppers. 

663,234 

Dec.  4,  1900 

lens  P.  Lihme, 
Cleveland,  Ohio. 

Preserved  wood  and  process  of  pre- 
paring same. 

756,173 

Mar.  29,  1904 

John  T.  Lloyd, 
New  York,  N.  Y. 

Vulcanizing  wood. 

566,591 

Aug.  25,  1896 

Fred.  A.  Lobert, 
National  City,  Cal. 

Compound  for  preserving  timber. 

546,960 

Sept.  24,  1895 

Rembrandt  Lockwood, 
Brooklyn,  N.  Y. 

Improvement  in  processes  of  treat- 
ing wood. 

174,914 

Mar.  21,  1876 

John  Thos.  Logan, 
Texarkana,  Tex. 

Process  of  preserving  wood. 

831,793 

Sept.  25,  1906 

J.  T.  Logan, 
Texarkana,  Tex. 

Apparatus    for    treating   the   butt- 
ends  of  logs. 

836,592 

Nov.  20,  1906 

John  Loomis, 
Jeffersonville,  Ind. 

Solution    for    seasoning    and    pre- 
serving wood. 

273,861 

Mar.  13,  1883 

Ira  Loughborough, 
Pittsford,  N.  Y. 

Apparatus  for  saturating  railroad 
ties. 

533,543 

Feb.  5,  1895 

Cuthbert  B.  Lowry, 
Lexington,  Ky. 

Wood  impregnation. 

831,450 

Sept.  18,  1906 

Cuthbert  B.  Lowry, 
Lexington,  Ky., 
Richard  Bernhard, 
Chicago,  111. 

Means  for  withdrawing  and  con- 
densing vapors. 

902,097 

Oct.  27,  1908 

M.  A.  Luckenbach, 
Denver,  Col. 

Process  of  treating  wood  to  prevent 
decay. 

473,705 

Apr.  26,  1892 

Geo.  A.  Ludington 
Akron,  Ohio. 

Method  of  vulcanizing  tires  in  con- 
tinuous lengths. 

754,078 

Mar.  8,  1904 

APPENDICES  289 

List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Gregory  Lukins, 
Sweetwater,  111. 

Preserving  wood. 

•L 

245,845 

Aug.  16,  1881 

Antionette  Macauley, 
Ft.  Dodge,  Iowa. 

Wood-preserving  compound. 

778,321 

Dec.  27,  1904 

J.  C.  Mallonee, 
Charleston,  S.  C. 

Process  of  preserving  wood. 

386,999 

July  31,  1888 

Ernst  Marmetschke, 
Schopfurth  near 
Eberswalde,  Ger. 

Method    of    impregnating    timber 
and  the  like. 

898,246 

Sept.  8,  1908 

J.  C.  Marshall, 
Oakland,  Cal. 

Wood-preserving  compound. 

259,030 

June  6,  1882 

J.  A.  Mathieu, 
Detroit,  Mich. 

Apparatus   for  preserving  railway 
ties. 

332,097 

Dec.  8,  1885 

H.  G.  McGonegal. 
Washington,  D.  C. 

Improvement  in  apparattus  for  pre- 
serving wood. 

140,520 

July  1,   1873 

Jas.  McKeon, 
Oakland,  Cal. 

Process  of  preserving  timber. 

461,365 

Oct.   13,   1891 

John  McLachlan, 
Chicago,  111. 

Process  of  solidifying  wood. 

575,973 

Jan.  26,   1897 

A.  R.  McNair, 
New  York,  N.  Y. 

Improvement  in  preserving   wood 
from  decay  and  mildew. 

94,626 

Sept.  7,  1869 

Wm.  K.  Miller, 
Canton,  Ohio. 

Improvement  in  burial  cases. 

57,545 

Aug.  28,  1866 

E.  P.  Morong, 
Boston,  Mass. 

Improvement  in  preserving  wooden 
pavements. 

134,479 

Dec.  31,  1872 

L.  D.  Mott, 
Marshalltown,  la. 

Compound  for  preserving  wood  and 
metal. 

251,918 

Jan.  3,   1882 

H.  G.  Muller, 
San  Francisco,  Cal. 

Preserved  wood. 

236,065 

Dec.  28,  1880 

Peter  Murray, 
Seattle,  Wash. 

Method  of  preserving  timber. 

495,991 

Apr.  25,  1893 

H.  C.  Myers, 
Cleveland,  Ohio. 

Method  of  vulcanizing  wood. 

537,393 

Apr.  9,  1895 

Robt.  Newell, 
Philadelphia,  Pa. 

Improvement    in    compounds    for 
coating  wood  and  other  articles  to 
render  them  acid  proof. 

140,530 

June  21,  1873 

B.  R.  Nickerson, 

San  Francisco,  Cal. 

Improvement    in    preserving    and 
hardening  wood. 

107,620 

Sept.  20,  1870 

19 


290        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Wm.  C.  Jones, 
W.  J.  R.  Stratford, 
F.  B.  Byrnes,  and 
E.  J.  Nixon, 
Texarkana,  Tex. 

Process  of  saturating  wood. 

216,286 

Nov.  7,  1905 

Patrick  O'Brien, 
South  Bend,  Ind. 

Improvement  in  processes  for  pre- 
paring the  surface  of  wood-work  of 
carriages. 

175,621 

Apr.  4,  1876 

John  Oliver, 
Toronto,  Can. 

Improvement    in    preserving    and 
drying  lumber. 

142,347 

Sept.  2,  1873 

Geo.  Palmer 
Littlestown,  Pa. 

Improvement  in  preserving  wood. 

49,146 

Aug.  1,  1865 

Chas.  W.  Parker, 
Genesee  Fork,  Pa. 

Preserving  posts,  etc. 

378,459 

Feb.  28,  1888 

Wm.  D.  Patten, 
New  York,  N.  Y. 

Fireproofing  compound. 

802,311 

Oct.  17,  1905 

Jos.  Paul,  and 
Ira  Hayford, 
Boston,  Mass. 

Improved  process  of  treating  wood 
to  preserve,  season  and  give  it  a 
better  surface. 

95,583 

Oct.  5,   1869 

Chas.  Payne, 
South  Lambeth,  Eng. 

Improvement  in  processes  for  pre- 
serving wood. 

7,399 

May  28,  1850 

Wm.  T.  Pelton, 
New  York,  N.  Y. 

Improvement    in    portable    appa- 
ratus for  preserving  wood. 

113,338 

Apr.  4,  1871 

Wm.  T.  Pelton, 
New  York,  N.  Y. 

Improvement     in     apparatus     for 
seasoning  and  preserving  wood. 

124,080 

Feb.  27,  1872 

Herbert  Elmer  Percival, 
Houston,  Tex. 

Wood-preserving  compound. 

891,726 

June  23,  1908 

Saml.  R.  Percy, 
New  York,  N.  Y. 

Preserving  wood. 

249,856 

Nov.  22,  1881 

Josef  Pfister, 
Vienna,  Austria-Hungary. 

Method  of  preserving  timber. 

683,792 

Oct.   1,   1901 

Josef  Pfister, 
Vienna,  Austria-Hungary. 

Process  of  staining  woods. 

708,069 

Sept.  2,  1903 

Josef  Pfister, 
Vienna,  Austria-Hungary. 

Apparatus     for     impregnating     or 
staining  wood. 

735,019 

July  28,   1903 

Geo.  Phillips, 
Key  West,  Fla. 

Coating  for  wooden  structures. 

414,247 

Nov.  5,  1889 

Geo.  Phillips, 
Key  West,  Fla. 

Process  of  preserving  wood. 

414,249 

Nov.  5,  1889 

APPENDICES 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


291 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

A.  M.  Pierce, 
Brooklyn,  N.  Y. 

Process  of*  fireproofing  wood. 

*& 

737,468 

Aug.  25,  1903 

Wm.  Powell, 
Liverpool,  Eng. 

Vulcanized    wood    and   process    of 
vulcanizing  same. 

755,240 

Mar.  22,  1904 

Theo.  Pridham, 
Petersham, 
New  So.  Wales. 

Coating  for  timber. 

453,821 

June  9,  1891 

D.  R.  Prindle, 
East  Bethany,  N.  Y. 

Improved    process    of    preserving 
wood  and  timber. 

63,300 

Mar.  26,  1867 

Thos.  N.  Prudden, 
San  Francisco,  Cal. 

Method  and  apparatus  for  protect- 
ing marine  wooden  structures. 

855,588 

June  4,  1907 

A.  D.  Purinton, 
Dover,  N.  H. 

Improved  composition  for  setting 
posts,  timbers,  etc. 

78,691 

June  9,  1868 

Geo.  Pustkuchen, 
Hoboken,  N.  J. 

Improved    apparatus    for    impreg- 
nating wood  with  tar  and  other 
materials. 

64,703 

May  14,  1867 

Jos.  W.  Putman, 
New  Orleans,  La. 

Apparatus   for   treating   wood   for 
preserving  it. 

247,947 

Oct.  4,   1881 

Jos.  W.  Putman, 
New  Orleans,  La. 

Apparatus  for  treating  timber  with 
antiseptics. 

266,516 

Oct.  24,   1882 

Jos.  W.  Putman, 
New  Crleans,  La. 

Compound  for  preserving  timber. 

404,302 

May  28,  1889 

Jos.  W.  Putman, 
New  Crleans,  La. 

Wood-preserving  compound. 

405,907 

June  25,  1889 

Randolph.  F.  Radebaugh, 
Tacoma,  Wash. 

Process  of  and  apparatus  for  treat- 
ing wooden  stopples. 

535,770 

Mar.  12,  1895 

Frederick  Ransome, 
Ipswich,  Great  Britain. 

Improvement  in  preserving  timber. 

55,216 

May  29,  1866 

John  M.  Reid, 
Allegheny  City,  Pa. 

Improvement  in  preserving  wood. 

154,767 

Sept.  8,   1874 

Peter  C.  Reilly, 
Indianapolis,  Ind. 

Preserved    wood    and    method    of 
making  same. 

901,557 

Oct.  20,   1908 

Peter  C.  Reilly, 
Indianapolis,  Ind. 

Preserved  wood. 

899,904 
899,905 

Sept.  29,  1908 

R.  P.  Reynolds, 
Walla  Walla,  Wash. 

Timber  preservative. 

792,458 

July  13,  1905 

H.  L.  Ricks, 
Eureka,  Cal. 

Method    of    preserving    submeged 
timbers. 

380,820 

Apr.  10,  1888 

292        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  ot 
inventor 

Title  of  patent                       J^°[ 

Date  issued 

Saml.  Ringgold,  Fla.  and 
Edw.  Earle, 
Savannah,  Ga. 

Improved  mode  of  preserving  tim- 
ber by  boiling  the  same  in  lime- 
water. 

877 

Aug.  6,  1838 

L.  S.  Robbins, 
New  York,  N.  Y. 

Improved    process    for    preserving 
wood. 

47,132 

Apr.  4,  1865 

L.  S.  Robbins, 
New  York,  N.  Y. 

Improved      mode      of      preserving 
telegraph  poles. 

89,345 

Apr.  27,  1869 

L.  S.  Robbins, 
New  York,  N.  Y. 

Improvement  in  processes  for  pre- 
serving wood. 

165,768 

July  20,  1875 

L.  S.  Robbins, 
Elizabeth,  N.  J. 

Improvement  in  processes  and  ap- 
paratus  for   preserving    wood    or 
lumber. 

217,022 

July  1,   1879 

L.  S.  Robbins, 
New  York,  N.  Y. 

Preserving  wood. 

9,512 

Dec.  21,  1880 

J.  G.  Robinson, 
Brooklyn,  Ala. 

Fence-post. 

655,638 

Aug.  7,  1900 

W.  W.  Robinson, 
Ripon,  Wis. 

Process  of  preserving  wood. 

294,676 

Mar.  4,  1884 

H.  N.  Roge, 
Edouard  Poret, 
Pierre  Baffoy,  and 
Pierre  Dupre, 
Paris,  France. 

Improvement  in  processes  of  pre- 
serving wood  and  other  vegetable 
matters. 

191,257 

May  29,  1877 

Jas.  Rowe, 
San  Francisco,  Cal. 

Composition  for  protecting  piles. 

440,832 

Nov.  18,  1890 

Sam'l.  M.  Rowe, 
Chicago,  111. 

Door    mechanism    for     creosoting 
tanks. 

908,144 

Dec.  29,  1908 

Karl  Rucker, 
Zernsdorf,  Ger. 

Method  of  fireproofing  wood. 

691,812 

Jan.  28,  1902 

Max  Ruping, 
Charlottenburg,  Ger. 

Method  of  impregnating  wood. 

707,799 
709,799 

Sept.  23,  1902 

Julius  Rutgers, 
Berlin,  Germany. 

Wood-impregnating  compound  and 
method  of  making  same. 

662,310 

Nov.  20,  1900 

Emile  Sabathe,  and 
Louis  Jourdan, 
Paris,  France. 

Improvement       in      impregnating 
substances  with  preservative 
material. 

58,036 

Sept.  11,  1866 

Thos.  H.  Sampson 
New  Orleans,  La. 

Process  of  preserving  lumber. 

403,144 

May  14,  1889 

APPENDICES 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


293 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

J.  L.  Samuels, 
San  Francisco,  Cal. 

Improved^  composition  for  prepar- 
ing and  hardening  wood  and  pre- 
serving the^ame. 

60,794 

Jan.   1,   1867 

Chr.  Schallberger, 
Seattle,  Wash. 

Compound  for  protecting  timber. 

678,201 

July  9,  1901 

Chr.  Schallberger, 
Vancouver,  Can. 

Wood-preserving  compound. 

714,521 

Nov.  25,  1902 

Julius  Schenkel, 
Dortmund,  Ger. 

Process  of  impregnating  wood. 

655,459 

Aug.  7,  1900 

Julius  Schenkel, 
Dortmund,  Ger. 

Process  of  fireproofing  wood. 

647,428 

Apr.  10,  1900 

P.  Schmidt, 

Preserving  wood. 

4,560 

June  6,  1846 

Jos.  Schneible, 
New  York,  N.  Y. 

Method  of  and  apparatus  for  sat- 
urating corks. 

599,798 

Mar.    1,    1898 

Chas.  A.  Seely, 
New  York,  N.  Y. 

Improved  method  of  impregnating 
wood  with  oleaginous  and  saline 
matters. 

69,260 

Sept.  24,  1867 

Jos.  A.  Sewall, 
Denver,  Colo. 

Process  of  preserving  wood. 

374,208 

Dec.  6,  1887 

A.  J.  Sheldon, 
Buffalo,  N.  Y. 

Improvement  in  preserving  wood. 

106,625 

Aug.  23,  1870 

Morris  Sherman, 
Chattanooga,  Tenn. 

Means  for  securing  heads  to  boilers, 
cylinders,  etc. 

781,371 

Jan.  31,   1905 

S.  L.  Shuffleton, 
Seattle,  Wash. 

Method  of  protecting  wooden  piles. 

676,704 

June  18,  1901 

J.  E.  Siebel, 
Chicago,  111. 

Improvement  in  depilating  hides 
and  preserving  wood. 

116,638 

July  4,   1871 

H.  V.  Simpson, 
London,  Eng. 

Fireproofing  wood. 

646,101 

Mar.  27,  1900 

H.  V.  Simpson, 
London,  Eng. 

Process  of  fireproofing  wood. 

668,227 

Feb.  19,  1901 

Archibald  J.  Sinclair, 
Chicago,  111. 

Process  of  coating  porous  material 
with  asphalt. 

893,391 

July  14,  1908 

Smith  A.  Skinner, 
Hoosick  Falls,  N.  Y. 

Cordage  and  twine  to  be  used  in 
binding  sheaves  of  grain. 

255,040 

Mar.  14,  1882 

Bat  Smith 
Spanish  Camp,  Tex. 

Composition  for  preserving  wood. 

244,327 

July  12,  1881 

294        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

Geo.  B.  Smith, 
Philadelphia,  Pa 

Improvement  in  apparatus  for  pre- 
serving wood. 

160,846 

Mar.  16,  1875 

Geo.  B.  Smith, 
Philadelphia,  Pa. 

Improvement  in   wooden   shingles 
made  fire-proof. 

199,001 

Jan.  8,   1878 

W.  B.  Smith, 
La  Fayette,  111. 

Improved  apparatus  for  saturating 
timber. 

62,295 

Feb.  19t  1867 

W.  H.  Smith, 
Steubenville,  Ohio. 

Improvement  in  apparatus  for  in- 
jecting  preservative   liquids   into 
wood. 

111,784 

Feb.  14,  1871 

W.  L.  Smith, 
New  York,  N.  Y. 

Apparatus  for  impregnating  wood. 

711,080 

Cct.   14,   1902 

P.  S.  Smout, 
Everett,  Wash. 

Composition    for    preserving    piles 
and  timber. 

806,591 

Dec.  5,  1905 

Edw.  Spaulding, 
Brooklyn,  N.  Y. 

Improved  process  for  treating  wood 

77,777 

May  12,  1868 

S.  F.  Spaulding, 
Jerico,  Conn. 

Improvement  in  preparing  veneers 
for  butter-boxes. 

164,945 

June  29,  1875 

Geo.  Speiz, 
Dutch  Kills,  N.  Y.. 

Preserving  wood. 

387,375 

Aug.    7,    1888 

Chas.  F.  Spicker, 
New  York,  N.  Y. 

Improvement  in  coloring  and  hard- 
ening wood. 

3,635 

June  24,  1844 

I.  B.  Sprague, 
Everett,  Wash. 

Process  of  preserving  wood. 

694,212 

Feb.  25,  1902 

Jas.  D.  Stanley, 
Eastover,  S.  C. 

Device    for    charring    surface     of 
timber. 

361,095 

Apr.  12,  1887 

Jas.  D.  Stanley, 
Wilmington,  N.  C. 

Apparatus  for  charring  timber. 

282,395 

July  31,  1883 

Jas.  D.  Stanley, 
Eastover,  S.  C. 

Device  for  charring  logs. 

361,193 

Apr.  12,  1887 

Chas.  W.  Stanton, 
Mobile,  Ala. 

Apparatus  for  steaming  wood. 

735,608 

Aug.  4,  1903 

Adolphe  Ste.    Marie   and 
Alfred  Hoffman, 
Lyons,  France. 

Process  of  seasoning  wood. 

675,500 

June  4,  1901 

Jas.  C.  Stead, 
Jersey  City,  N.  J. 

Improvement  in  apparatus  for  pre- 
serving wood. 

148,630 

Mar.  17,  1874 

L.  M.  Stern  and  Edw.  M. 
Kempner,  Buffalo,  N.  Y. 

Apparatus  for  impregnating  wood. 

662,104    Nov.  20,  1900 

APPENDICES 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


295 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

F.  A.  Stevens, 
Chicago,  111. 

Improvenient  in  apparatus  for  pre- 
serving wAVrd. 

102,725 

May  3,  1870 

Chas.  Stollberg, 
Toledo,  Ohio. 

Sheet-metal      sap      receptacle      or 
'vessel. 

857,846 

June  25,  1907 

Richard  Sutphen, 
Freehold,  N.  J. 

Improvement    in    wood-preserving 
compositions. 

120,009 

Oct.  17,  1871 

Geo.  W.  Swan, 
San  Francisco,  Cal. 

Improvement  in  the  processes  for 
softening  and  toughening  blocks  of 
wood. 

142,298 

Aug.  26,  1873 

Wm.  Taggart, 
San  Francisco,  Cal. 

Preserving  piles. 

261,045 

July  18,  1882 

A.  H.  Tait, 
Jersey  City,  N.  J. 

Improvement  in  preserving  wood. 

115,784 

June  6,  1871 

Rudolf  Tanczos, 
Vienna,  Austria-Hungary. 

Fireproofing  wood. 

329,973 

Nov.  10,  1885 

Chas.  Taylor,  R.  I.  Murch- 
ison,    and  Geo.    Sharpe, 
Melbourne,   Victoria. 

Composition  for  preserving  timber. 

391,209 

Oct.  16,  1888 

J.  H.  Taylor, 
New  York,  N.  Y. 

Improved    process    of    preventing 
decay  in  wood. 

70,761 

Nov.  12,  1867 

Wm.  B.  Taylor, 
Winterpark,  Fla. 

Composition  for  preserving  wood. 

759,938 

May  17,  1904 

L.  N.  Teachman, 
Lincoln,  Nebr. 

Wood-preserving  composition. 

277,810 

May  15,  1883 

Horace  Thayer, 
Warsaw,  N.  Y. 

Treating  wood  for  the  manufacture 
of  boxes,  cases,  etc.- 

45,537 

Dec.  20,  1864 

Waldemar  Thilmany, 
Cleveland,  Ohio. 

Improvement  in  apparatus  for  im- 
pregnating timber  with  antiseptics. 

177,770 

May  23,  1876 

Waldemar  Thilmany, 
Cleveland,  Ohio. 

Improvement  in  processes  for  pre- 
serving timber. 

202,678 

Apr.  23,  1878 

Nathan  H.  Thomas, 
New  Orleans,  La. 

Improvement  in  processes  for  pre- 
serving wood. 

113,706 

Apr.  11,  1871 

A.  B.  Tripler, 
New  Orleans,  La. 

Improvement  in  preserving  wood. 

104,916 

June  28,  1870 

A.  B.  Tripler, 
New  Orleans,  La. 

Improvement  in  preserving  wood 
for  railroad  ties,  etc. 

104,917 

June  28,  1870 

A.  B.  Tripler, 
Philadelphia,  Pa. 

Improvement  in  processes  for  pre- 
serving wooden  pavements  from 
rot. 

126,592 

May  7,  1872 

296        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 
List  of  II.  S.  Patents  on  Wood  Preservation. — Continued 


Name  and  address  of 
inventor 

Title  of  patent 

No.  of 
patent 

Date  issued 

A.  B.  Tripler, 
New  York,  N.  Y. 

Improvement  in  processes  for  stain- 
ing wood. 

207,630 

Sept.  3,  1878 

A.  B.  Tripler, 
New  York.N.  Y. 

Improvement  in  the  art  of  preserv- 
ing wood. 

208,649 

Oct.    1,    1878 

Abel  D.  Tyler, 
Worcester,  Mass. 

Impregnating  wood. 

553,547 

Jan.  28,  1896 

Geo.  S.  Valentine, 
Brooklyn,  N.  Y. 

Process  of  and  apparatus  for  pre- 
serving wood  by  impregnation  to 
given  heights. 

285,087 

Sept.  18,  1883 

Rose  L.   Valleen, 

Seattle,   Wash. 
9 

Wood-preserving  compound. 

579,101 

Mar.  16,  1897 

G.  A.  Vivien  and 
Paul  C.  Vivien, 
Honfleur,  France. 

Improvement  in  compositions  for 
preserving    wood,     coating   ships' 
bottoms,  etc. 

123,801 

? 

J.  G.  Voorhees, 
Aqueduct  Mills,  N.  J. 

Improvement  in  preserving  wood. 

121,141 

Nov.  21,  1871 

Martin  Voorhees,  Prince- 
ton, and  G.  W.  N.  Custis, 
Camden,  N.  J. 

Improved  process  and  apparatus  for 
seasoning  and  impregnating  wood 
with  preservative  material. 

87,226 

Feb.  23,  1869 

John     F.     Walter,     Jr., 
Brooklyn,  N.  Y. 

Process    of    drying    and    seasoning 
lumber. 

287,351 

Oct.  23,  1883 

Fred  J.  Warren, 
Newton,  Mass. 

Wooden  block  pavement. 

794,758 

July  18,  1905 

Chas.  G.  Waterbury, 
New  York,  N.  Y. 

Improvement  in  processes  for  hard- 
ening and  preserving  wood. 

124,402 

Mar.  5,  1872 

Ezra    Webb, 
New    York,  N.  Y. 

Improvement  in  preserving  wood. 

108,659 

Oct.  25,  1870 

Peter    Welch, 
St.    Louis,  Mo. 

Improvement  in  preserving  wood. 

129,503 

July  16,  1872 

Wm.  Wellhouse,  &  Erwin 
Hagen,  St.  Louis,  Mo. 

Improvement  in  preserving  wood. 

216,589 

June  17,  1879 

Pelag  Werni, 
Philadelphia,  Pa. 

Improvement    in    compounds    for 
preserving  wood. 

164,786 

June  22,  1875 

S.  P.  Wheeler, 
Bridgeport,    Conn. 

Improvement  in  the  manufacture  of 
articles  of  compressed  wood. 

101,552 

Apr.   5,    1870 

S.  P.  Wheeler, 
Bridgeport,  Conn. 

Improved  process  of  treating  wood. 

101,553 

Apr.   5,    1870 

APPENDICES 
List  of  U.  S.  Patents  on  Wood  Preservation. — Continued 


297 


Name  and  address  of 
inventor 

Title  of  'patent 

No.  of 
patent 

Date  issued 

Thos.   B.  White, 
Warsaw,  Mo. 

Post-protector. 

I  ; 

868,953 

Oct.  22,  1907 

Sidney  S.  Williams, 
Providence,  R.  I. 

Apparatus  for  use  ^treating  wood. 

904,589 

Nov.  24,  1908 

Sigmund  Willner, 
London,  Eng. 

Apparatus  for  impregnating  wood. 

620,627 

Mar.  7,  1899 

Sigmund  Willner, 
London,  Eng. 

Apparatus  for  impregnating  wood. 

676,060 

June  11,  1901 

Sigmund     Willner, 
New  York,  N.  Y. 

Apparatus  for  impregnating  wood. 

771,689 

Oct.   4,    1904 

Sigmund    Willner, 
Memphis,  Tenn. 

Apparatus   for  forcing   fluids   into 
wood. 

807,411 

Dec.  12,  1905 

Sigmund     Willner, 
Chicago,  111. 

Apparatus  for  injecting  chemicals 
into  logs. 

896,785 

Aug.  25,  1908 

Jas.    P.    Witherow, 
Pittsburg,  Pa. 

Process  of  and  apparatus  for  vul- 
canizing wood. 

446,501 

Feb.  17,  1891 

Jas.    P.    Witherow, 
Pittsburg,  Pa. 

Apparatus  for  vulcanizing  wood. 

446,500 

Feb.  17,  1891 

Jas.  H.  Young, 
New,  York,  N.  Y. 

Apparatus  for  impregnating  wood. 

329,799 

Nov.  3,  1885 

Wm.  Youngblood, 
Jamaica,  N.  Y. 

Method  of  preserving  wood. 

398,366 

Feb.  19,  1889 

METHOD  OF  ANALYZING  ZINC  CHLORIDE1 

Sampling. — A  fair  average  sample  must  be  taken  from  one  out 
of  every  ten  drums.  Quickly  transfer  the  sample  to  a  clean,  dry. 
salt-mouthed  bottle,  stopper,  hermetically  seal  and  send  to  the 
laboratory  for  test.  The  sample  should  be  marked  with  a 
number  or  other  device,  corresponding  to  the  drum  or  lot  from 
which  it  was  taken. 

Insoluble  Basic  Zinc  Chloride. — Pulverize  about  10  grams  of 
the  fused  zinc  chloride  by  crushing  between  filter  papers,  and 
quickly  transfer  to  a  weighing  bottle.  This  operation  must  be 
performed  quickly,  owing  to  the  deliquescent  nature  of  the  sub- 
stance. Weigh  the  bottle  plus  the  sample,  transfer  the  sample  to 
500  c.c.  of  water  in  a  beaker,  and  weigh  the  bottle  again;  the 

1  From  the  Proceedings  of  the  American  Wood  Preservers'  Association. 

20 


298        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 

weight  of  the  sample  is  thus  obtained  by  difference.  Cover  the 
beaker  and  allow  the  solution  to  stand  for  12  hours. 

Filter  through  a  weighed  Gooch  crucible  into  a  liter  flask. 
Wash  the  residue  with  cold  water  until  it  is  free  from  chlorides. 
Dry  the  basic  zinc  chloride  at  100°  C.  for  about  12  hours  and 
weigh. 

Dilute  the  filtrate  to  1000  c.c.  and  mix  thoroughly. 

Ferric  Chloride. — Take  100  c.c.  of  the  solution,  boil,  and  pre- 
cipitate the  iron  with  ammonium  hydroxide.  Boil  off  the  excess 
of  ammonia,  filter  and  reject  the  filtrate.  Dissolve  the  precipi- 
tate off  the  paper  with  hot  dilute  hydrochloric  acid,  and  reprecipi- 
tate  with  ammonium  hydroxide.  Filter  through  the  original 
filter  paper.  Wash  the  ferric  hydroxide  5  to  6  times  with  hot 
water j  ignite  and  weigh  as  Fe203. 

Factor  for  metallic  iron,  7. 

Factor  for  ferric  chloride,  1.0156. 

Soluble  Zinc; — Take  50  c.c.  of  the  original  solution,  and  add  a 
concentrated  solution  of  sodium  carbonate,  until  the  solution  is 
slightly  alkaline.  Zinc  is  precipitated  as  basic  carbonate. 
Boil  for  15  minutes.  Decant  through  a  weighed  Gooch  crucible 
and  wash  by  decantation  three  or  four  times.  Ignite  at  a  high 
temperature  and  weigh  as  ZnO.  Subtract  the  percentage  of 
ferric  oxide  found  above. 

Factor  for  metallic  zinc,  0.8034. 

Factor  for  zinc  chloride,  1.7644. 

Free  Acid.' — Dissolve  10  grams  of  the  fused  chloride  in  100  c.c. 
of  distilled  water,  and  test  with  methyl  orange.  If  free  acid  is 
present,  which  is  rarely  the  case,  determine  by  titration  with 
standard  alkali.  Factor,  chlorine  from  hydrochloric  acid,  0.973. 

Total  Soluble  Chlorine. — Titrate  25  c.c.  of  the  solution  with 
standard  silver  nitrate,  using  potassium  chromate  as  indicator. 
Subtract  the  amount  of  chlorine  equivalent  to  the  free  hydro- 
chloric acid  present,  if  any,  and  also  the  chlorine  combined  as 
ferric  chloride,  and  calculate  the  remainder  to  zinc  chloride, 
by  using  the  factor  2.04.  The  amount  of  zinc  chloride  thus 
obtained  should  check  with  that  found  from  soluble  zinc. 

RECORDS  ON  THE  LIFE  OF  TIMBERS 

Mine  Timbers. — The  U.  S.  Forest  Service  treated  a  large  num- 
ber of  mine  timbers  according  to  various  methods  and  placed 


APPENDICES 


299 


them  in  the  coal  mines  of  the  Philadelphia  and  Reading  Coal 
and  Iron  Company  at  Pottsville,  Pa.     Inspections  were  made 


Description  of  Material 


Condition  of  Material 


Legend 


Sound 

Partly  Decayed,  Still  Serviceable 

Entirely  Decayed,  to  be  Eemoved,  not  Serviceable 

Removals  Due  to  aU  Causes 


FIG.  30. — Comparative  condition  of  treated  and  untreated  loblolly  pine 
gangway  sets  placed  in  the  mines  of  the  Philadelphia  and  Reading  Coal 
and  Iron  Co. 

each  year  for  4  years  with   the   results  graphically  shown  in 
Fig.  30.1 
Paving  Blocks. — In  January,  1910,  the  American  Association 

1  Bulletin  107,  U.  S.  Forest  Service. 


300        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


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APPENDICES 


301 


of  Creosoted  Wood  Blocks  Paving  Manufacturers  sent  inquiries 
to  various  American  cities  to  learn  their  experiences  with  wood- 
block paving.     The  replies  are  summarized  in  Table  41. 
TABLE  41. — EXPERIENCE  OF  SOME  CITIES  WITH  WOOD-BLOCK  PAVING 


City 

Years  of  service 
at  last  inspec- 
tion. 

Condition 

Authority 

Brooklyn  

7 

Good 

J.  C.  Sheridan 

New  Orleans  

31 

Blocks  good 

R.  E.  Slade 

Minneapolis 

8 

No  repairs 

E  R  Button 

St  Louis 

7 

Excellent 

J  C  Travilla 

Duluth  

5 

No  repairs 

T.  F.  McGilvray 

Des  Moines  .   . 

4 

No  repairs 

J.  MacVicar 

Toledo 

9 

No  repairs 

G.  W  Touson 

Detroit  

5 

No  repairs 

R.  H.  McCormick 

Grand  Rapids,  Mich..  . 

9 

Excellent 

L.  W.  Anderson 

Poles. — About  1000  chestnut  poles  treated  in  various  ways 
were  set  by  the  U.  S.  Forest  Service  in  1905  in  cooperation  with 
the  American  Telephone  and  Telegraph  Company  in  Pennsyl- 
vania. The  results  after  5  years  of  service  are  shown  in  Fig.  3 1.1 


Description  of  Experiment 


Method 

Character 

of 

of 

Sold  as 

Treating 
Material 

Ground 
where  Set 

Crushed 

Spirittine 

Brush 

Stone 

—  —  —  —  — 
«_ 

0.5  1.0  1.5  2.0 

Average  Loss  in  Circumferance  at  Ground  Line-Inches 

FIG.  32. — Condition   of   experimental   poles  in  the   Poughkeepsie-Newton 
Square  line  8  years  after  placement. 

A  similar  line  was  set  up  by  the  U.  S.  Forest  Service  in  New 
Jersey  in  1902.  All  the  poles  were  chestnut.  The  results  after 
8  years  of  service  are  shown  in  Fig.  32. 2 

The  German  government  has  kept  record  on  the  life  of  its 
poles  when  treated  by  various  processes,  these  records  extending 
over  a  period  of  about  50  years.  The  general  results  to  date  are 
shown  in  Table  42. 3 

1  Circular  198,  U.  S.  Forest  Service. 

2  Circular  198,  U.  S.  Forest  Service. 

3  Archiv  fiir  Post  und  Telegraphic. 


302        THE  PRESERVATION  OF  STRUCTURAL  TIMBER 


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APPENDICES 


303 


Cross  Ties. — The  reported  life  of  cross-ties  in  service  is  given 
in  Table  43,  which  is  taken  from  Bulletin  118  of  the  U.  S.  Forest 
Service. 

TABLE  43.- — REPORTED  LIFE  OP  TIES  IN  SERVICE 


Species 

Laid  by 

How  treated 

Life 

White  oaks  
Spruce  

Duluth  &  Iron  Range  Ry.  Co. 
Union  Rv.  Co.  (horse) 

Untreated 
Burnettized 

Years 
8  to  9 
8  to  20 

Pine  (probably 

[  A.,  T.  &S.  F.  Ry.  Co  

do 

10|  to  15 

western     yel- 

| T.  &  N.  O.  Ry.  Co  

do 

10  to  11 

low,   longleaf, 
and         pin  on 
pines). 
Baltic  pine  .... 

(  H.&T.  C.  Ry.  Co  
English  railroads  

Creosoted 
do 

19 
8  to  18 

C.  R.  R.  of  N.  J  . 

do 

15£ 

Hemlock  

•    C.,  R.  I.  &  P.  Ry.  Co  
Duluth  &  Iron  Range  Ry.Co. 
do.   ... 

Wellhouse 
Burnettized 
do 

10  to  15 
8  to  10 
94- 

Tamarack  
Beech  

Pittsburg,  Ft.  Wayne  &  Chi- 
cago Ry.  Co. 
French,    German,   and  Aus- 

Wellhouse 
{Untreated 

8.84 
4  to  5 

trian  railroads 
f  C.  R.  R.  of  N.  J  

Burnettized 
Creosoted 
Burnettized 

10  to  12 
18  to  30 
15  + 

Maple  

(German  railroads 

do 

16 

Wabash  R.  R  

do  

5  to  6 

Red  oaks  

French  and  German  railroads 

Creosoted 

19  to  25 

INDEX 


Abrasion,  importance  of,  25 

protection  of  ties  from,  141 
Absorption,  effect  of  density  of  wood 

upon,  31 

difficulty  in  measuring,  116 
measured  by  gages  and  scales, 

103 

variation  in  different  woods,  138 
of  preservatives    (see    penetra- 
tion) 

A.C.W.  process,  description  of,  59 
Aczol,  description  of,  253 
Adzing,  advantages  of  before  treat- 
ment, 147 
machines,   apparatus  and   cost 

of,  106 

Air  pressure,  effect  of  upon    treat- 
ment, 112 
pumps,  cost  and  use  of  in  plants, 

97 

seasoning,  description  of,  44 
Alkaline  soils,  action  upon  wood,  26 

soils,  decay  of  wood  in,  221 
Allardyce  process,  description  of,  63 
Allis-Chalmers  Co.,  table  on   plant 

costs,  125 

American  Ry.  Eng.  Ass'n,  specifica- 
tions for  creosote,  83,  261 
Ammonium  chloride,  as  a  fire  retard- 
ant,  216 

Analysis,  of  creosote,  261 
of  zinc  chloride,  297 
Anchors,  construction  of,  93 
Angier,    F.    J.,   on  the    use   of   air 

pumps,  97 

on  grouping  ties,  138 
Annual  ring,  definition  of,  34 
Asbestos  packing,  use  of  in  doors,  94 
Association  for  Standardizing  Pav- 
ing Spec.,  specifications  for 
creosote,  84 


305 


B 

Bailey,   I.   W.,  experiments  of,   on 

penetration,  38 
Bark,  necessity  for  peeling,  41 

effect  of  on  life  of  piling,  183 
Barrels,  used  for  open  tank  plants, 

89 

Barns,  paving  blocks  in,  204 
Bateman,  E.,  method  for  analyzing 

zinc  chloride,  74 

Bethell  process,  description  of,  56 
Birds,  destruction  of  wood  caused 

by,  27 

protection  against,  221 
Bleeding,  of  wood  blocks,  201 
Block   signals,   use   of   treated   ties 

between,  241 
Blocks,  equipment  for  making,  105 

oil  for,  84 

B.M.  Process,  description  of,  249 
B.M.   Preservative,   description  of, 

253 

Boats,  preservation  of,  186 
Boiling,    effect    of    on    strength    of 

wood,  229 

Boiler  house,  construction  of,  98 
Boiling  process,  description  of,  57 
Bolts,  use  of  in  doors,  94 
Bolt  doors,  construction  of,  94 
Borax,  as  a  fire  retardant,  216 
Boring  ties,  machines  for,  106 

effect  of,  in  holding  spikes,  146 
Boring,  holes  in  posts  to    preserve 

them,  175 
Boucherie  process,  for  treating  poles, 

163, 

Bridge  timbers,  substitutes  for,  246 
Brush  treatments,  description  of,  51 
Brush  treatments,  for  poles,  160 

for  posts,  175 

Buehler  process,  description  of,  58 
Buggies,  (see  cars) 


306 


INDEX 


Buildings,  methods  of  treating  lum- 
ber in,  209 

substitution  for  wood  in,  247 
Builders,  of  treating  plants,  261 
Burlap,  used  in  protecting  piling,  183 
Burnett  process,  description  of,  60 
Burnett,  Wm.  73 

Butterfield,  J.  T.,  tests  on  the  elec- 
trical resistance  of  wood, 
234 


Canals,  use  of  in  plants,  100 
Capital,  invested  in  wood  preserv- 
ing plants,  2 
Carbolineum,  Avenarius,  description 

of,  252 
Carbolineum,  S.P.F.,  description  of, 

252 

Carbolic  acid,  toxicity  of,  72 
Carbon,  in  creosote,  121 
Card  process,  description  of,  61 
Cars,  construction  of  cylinder,  100 
treatment  of  wood  in,  209 
substitutes  for  wood  in,  247 
C.  A.  Wood  Preserver,  description  of, 

252 

Cell  walls,  absorption  by,  32 
Cement,  used  in  protecting  piles,  184 
Charring,  as  a  means  of  preserving 

wood,  51 
poles,  160 
posts,  174 

Checks,  prevented  by  "S-irons"  158 
Chemical  composition  of  cell  wall, 

effect  of  on  penetration,  39 
Chicago  Creosoting  Co.,  design  of 

block  plant,  106 
Coal  tars,  discussion  of,  78 
Coal  tar  creosote,  composition  and 

value  of,  81 
specifications  for,  83 
Coils,  construction  of  in  retort,  93 
Compression,  of  wood  in  cylinder, 

117 

Concrete,  poles  set  in,  160 
Concrete  ties,  use  of,  244 
Conduits,  substitutes  for  wood,  248 


Conservation  of  timber,  affected  by 

preserving  wood,  2 
Consumption  of  wood  preservatives 

in  the  U.  S.,  259 
Copper  sulphate,  its  value  as  a  wood 

preservative,  71 

Copperized  oil,  description  of,  252 
Corrosion  of  steel,  by  preservatives, 

68 
Corrosion  of  spikes,  in  zinc  treated 

ties,  241 

Cost,  of  pressure  plants,  124 
of  treating  ties,  150 
of  treating  poles,  165 
of  treating  cross  arms,  170 
of  treating  mine  timbers,  192 
of  fireproofing  wood,  218 
of  treating  paving  blocks,  202 
of  treating  posts,  178 
of  treating  piling,    185 
of  treating  shingles,  207 
Cranes,  use  of  in  plants,  100 
Creo-resinate  process,  description  of, 

250 

Creoaire  process,  description  of,  251 
Creoline,  description  of,  254 
Creosotes,  their  value  as  wood  pre- 
servatives, 75 
classification  of,  77 
Creosote,  definition  of,  76 
evaporation  of,  67 
expansion  of,  due  to  tempera- 
ture, 117 

method  of  manufacture,  79 
Creosote  process,  (see  Bethell  proc- 
ess), 

Creosote,  as  a  fire  retardant,  219 
effect  on  the  strength  of  wood, 

230 

effect  on  human  skin,  82 
list  of  manufacturers  of,  254 
specifications  for,  261 
Forest  Service  method  of  analy- 
sis, 270 
Cresol-calcium   process,    description 

of,  251 

Cross  arms,  woods  used  for,  168 
methods  of  seasoning,  168 
manufacture  of,  168 


INDEX 


307 


Cross  arms,  economy  in  treating,  171 
cost  of  treating,  170 
treatment  of,  169 

Crude  oils,  value  of,  as  woodv  pre- 
servatives, 75 
Crude  oil,  for  treating  posts,  174 

effect  on  strength  of  wood,  231 
Crumby,  J.  J.,  on  the  life  of  posts, 

179 

Curtis,  W.  G.,  57 

Cutting  season,  effect  of,  on  treat- 
ment, 140 

Cylinder  cars,  construction  of,  100 
Cylinders,  (see  retorts) 
Cylinder,  expansion  of  due  to  tem- 
perature, 117 


Decay,  discussion  of,  15 
Decayed  poles,  reenf  or  cement  of,  164 
Density  of  wood,  effect  upon  pene- 
tration, 31 

Deterioration  of  timber,  discussion 

of  factors,  which  cause,  15 

Dipping  treatments,  description  of, 

52 

posts,  174 

Dock,  construction  of  loading,  99 
Doors,  construction  of  in  retorts,  94 
Durability,  of  green  and  seasoned 

wood,  43 

of  American  timbers,  275 
records  on  life  of  wood,  298 

E 

Economy,  in  treating  ties,  151 
poles,  166 
posts,  178 
piling,  186 
mine  timbers,  193 
Egypt,  history  of  wood  preservation 

in,  9 
Electrolysis,    in    protecting    piling, 

184 
Electrical,     resistance     of     treated 

wood,  234 
Empty  cell  process,  (See  Lowry  and 

Rueping  processes) 
Errors,  in  operating  plants,  116-120 


Europe,  history  of  wood  preservation 

in,  9 

Evaporation,  of  creosote,  67 
Expansion,  of  creosote  due  to  tem- 
perature, 117 


Factories,  paving  blocks  in,  204 

treatment  of  wood  in,  210 
Fence  posts,  (see  posts) 
Fiber-saturation  point,  definition  of, 

44,  225 

Final  vacuum,  effect  of,  109 
Fire-killed  timber,  utilization  of,  8 
Fire,  destruction  of  wood  caused  by, 

25,  213 
in  mines,  192 

Fire  protection,  in  plants,  105 
Fireproof ed  wood,  objections  to,  214 
Fireproofing  wood,  theory  of,  214 
methods  of,  215 
chemicals  used  in,  216 
tests  to  determine  the  efficiency 

of,  217 
cost  of,  218 

Fireproofing  plants,  list  of,  259 
Fir,  used  for  cross  arms,  168 
Form,  of  ties,  131 
Forest  management,  effect  of  wood 

preservation  upon,  3 
Forests,  composition  of  affected  by 

wood  preservation,  3 
Freight,     decreased     by    seasoning 

poles,  159 

Full-cell  process,  (see  Bethell  proc- 
ess) 
Fungi,  description  and  classification 

of,  16 
Furniture,    methods    of    protecting 

rustic,  211 

G 

Gerry,  Eloise,  experiments  on  ty lo- 
ses, 36 

Guissani  process,  description  of,  54 
Goltra,  W.  F.,  on  transfer  tables,  99 
Goltra  process,  description  of,  250 
Greeks,  on  methods  of  preserving 
wood,  9 


308 


INDEX 


Greenheart,  for  piling,  181 
Greenhouses,  treatment  of  wood  in, 

209 

Grouping,  value  of,  in  ties,  139 
Growth,  effect,  of  upon  treatment, 

141 
Gages,  location  and  construction  of, 

92 
use  of,  in  measuring  absorption, 

103 
Guard  rails,  construction  of,  93 

H 

Hatt,  W.  K.,  tests  on  the  strength  of 

spikes,  147 
effect  of  various  processes  on 

strength  of  ties,  233 
Hasselman  process,  description    of, 

250 

Heartwood,  effect  on  penetration,  33 
Hewn  ties,  (see  ties) 
Herodotus,  on  preservation  of  mum- 
mies, 9 

History,  of  wood  preservation,  9 
Holz-Helfer,  description  of,  253 
Humphrey,  C.  J.,  toxicity  test  by,  65 
Hunt,  G.  M.,  on  Boucherizing  poles, 
163 


Imperial    Wood    Preservative,    de- 
scription of,  254 

Inflammability,  of  wood  treated  with 

zinc  and  creosote,  219 
tests  to  determine,  of  wood,  217 

Initial  absorption,  difficulty  in  meas- 
uring, 116 

Insects,  destruction  of  wood  by,  18 
in  rustic  furniture,  211 

Inspector's    laboratory,    equipment 
for,  104 

Inspection,  of  treatments,  notes  on, 
122 

Isaacs,  J.  D.,  57 

K 

Kempfer,  W.  H.,  on  treating  poles, 

162 
Kickback,  significance  of,  118 


Kreodone,  description  of,  254 
Kyanizing,  description  of  process,  53 
for  poles,  163 


Laboratory,  need  for  an  inspector's, 

104 
Lagging,  the  retort,  advantages  of,  95 

treatment  of,  in  mines,  192 
Leakage,  prevention  of,  in  doors,  94 
Liebig,  on  theory  of  decay,  15 
Lightning  equipment,  in  plants,  105 
Limnoria,  description  of,  24 
Loading  dock,  (see  dock) 
Locustine,  description  of,  254 
Logs,    effect   of   wood   preservation 

upon  inferior,  8 
methods  of  preserving,  211 
Log  cabins,  methods  of  protecting, 

211 

Lowry  process,  description  of,  59 
Lumber,  methods  of  treating,  208 


M 


Machine  shop,  construction  of,  98 
Marine  borers,  description  of,  20 
Measuring  tanks,  types  of,  101 
Mechanical  abrasion,  destruction  of 

wood  by,  25 
Mercuric    chloride,    its   value   as   a 

preservative,  71 
Mine  timbers,  selection  of,  188 

manufacture  of,  189 

seasoning  of,  189 

methods  of  treatment,  190 

durability  of,  298 

cost  of  treating,  192 

economy  in  treating,  193 

substitutes  for,  245 
Mines,  danger  of  fire  in,  192 
Mixing  tanks,  construction  of,  101 
Moisture,  distribution  in  posts,  65 

effect  of  in  wood  on  treatment, 
140 

method  of  determining  in  creo- 

soted  wood,  273 
Mummies,  preservation  of,  9 


INDEX 


309 


N   '-': 

National  Electric  Light  Ass'n,  analy- 
sis of  creosote,  264 
specifications  for  water  gas  creo- 
sote, 85 

Nausitoria,  description  of,  21 

Newlin,  J.  H.,  experiments  in  driving 

spikes,  145 
tests  on  shrinkage,  226 

Nonpressure  process,  description  of, 
53 

N.  S.,  Special,  description  of,  254 


0 


Odor,  of  preservatives,  69 

Oil,  seasoning  in,  48 

Oils,  crude,  value  of,  75 

Oil  tars,  discussion  of,  78 

Operation,  of  plants,  89 

Open  tank  process,  description  of,  54 

Open  tank  plants,  types  of,  89 

list  of  in  U.  S.,  258 

Open  tank,  treatments  for  poles,  161 
Oxalic  acid,  as  a  fire  retardant,  216 


Packing,  for  retort  doors,  94 
Paint,  on  treated  wood,  69 

value  of  in  preserving  wood,  87 
Palmetto,  for  piling,  181 
Patents,  list  of,  for  preserving  wood, 

276 

Pavements,  efficiency  of  various,  197 
Paving  blocks,  manufacture  of,  105- 
198 

oil  for,  84 

troubles  with,  200 

expansion  of,  201 

methods  of  laying,  202 
Paving  blocks,  cost  of  treatment,  202 

history  of,  195 

woods  used  for,  197 

number  used,  196 

methods  of  treatment,  199 

advantages  of,  203 

for  barns  and  factories,  204 

durability  of,  299 


Penetration,  of  preservative,  effect 

of  structure  on,  31 
effect  of  sapwood  on,  33 
effect  of  heartwood  on,  33 
in  summerwood,  34 
in  springwood,  34 
efiect  of  vessels  upon,  35 
effect  of  tyloses  upon,  35 
effect  of  resin  ducts  upon,  36 
effect  of  pits  upon,  38 
effect  of  composition  of  cell  wall 

upon,  39 

effect  of  cell  slits  upon,  39 
of     various     preservatives     in 

wood,  70 

Peeling  timber,  necessity  for,  41 
Peeling  bark,  necessity  for,  37 
Perforations,  in  poles  to  aid  pene- 
tration, 161 
Petri  dish,  method  for  determining 

toxicity,  65 

Petroleum,  (see  crude  oils) 
Pettigrew,  experiments  with  mum- 
mies, 9 

Pholas,  description  of,  22 
Piling,  life  of,  16, 

woods  used  for,  181 
manufacture  of,  182 
methods  of  seasoning,  182 

treatment,  183 
cost  of  treating,  185 
economy  in  treating,  186 
substitutes  for  wood,  244 
Piping,  use  of  in  plants,  104 
Pitch  streaks,  in  preserving  posts, 

177 

Pits,  effect  on  penetration,  38 
Plants,  construction  and  operation 

of,  89 

cost  of  pressure,  124 
list  of  wood  preserving  in  U.  S., 

255 

Plates,  bearing  on  ties,  141 
Pliny,  on  Grecian  methods  of  pre- 
serving wood,  9 
Pole  borer,  description  of,  19 
Poles,  attacked  by  woodpeckers,  27 
woods  used  in  making,  156 
manufacture  of,  156 


310 


INDEX 


Poles,  perforations  in,  161 

seasoning  of,  156-158 

selection  of  species  for,  156 

shrinkage  in,  159 

saving  in  freight  due  to  season- 
ing, 159 

methods  of  treating,  159 
reinforcing  decayed,  164 

cost  of  treating,  165 

economy  of  treatment,  166 

life  of,  166-301 

substitutes  for,  244 
Pollution,  of  streams,  122 
Pores,  (see  vessels) 
Posts,  woods  used  in  making,  172 

method  and  time  of  cutting,  173 
of  seasoning,  173 

treatment  of,  174 

cost  of  treating,  178 

economy  in  treating,  178 

life  of,  179 

substitutes  for  wood,  245 
Powder  post  insects,  description  of, 

18 

Powell  process,  description  of,  250 
Preliminary  vacuum,  effect  of,  107 
Preliminary  air,  effect  of,  112 
Preservatives,  corrosive  action  of,  68 

properties  of  efficient,  64 

purity  of,  121 

used  in  treating  wood,  251 

amounts  used  in  U.  S.,  259 

toxicity  of,  66 

Preservol,  description  of,  252 
Pressure  plants,  essential  parts  of,  91 
Pressure,  effect  of,  on   treatments, 

115 
Pressure,  effect  of,   on  strength  of 

wood,  232 
Prince,  R.  E.,  on  fireproofing  woods, 

216 

Processes,  for  preserving  wood,  50 
Pump  house,  construction  of,  96 


Rails,  construction  of  guard,  93  m 
Receiving  tanks,  use  of,  101 
Records,  on  the  durability  of  timber, 
298 


Resin  ducts,  effect  upon  penetration, 

36 

Retorts,  construction  of,  91 
Retort  house,  construction  of,  91 
Robbins  process,  history  of,  13 

description  of,  250 
Roofs,  on  ties,  value  of,  135 
Rueping  process,  description  of,  60 
Rutgers  process,  description  of,  61 


Sapwood,  effect  on  penetration,  33 

distribution  on  ties,  132 

absorption  by,  138 
Sapwood  Antiseptic,  description  of, 

253 
Sap  stain,  damage  caused  by,  29 

protection  against,  222 
Sand  storms,  protection  against,  223 
Sawmill,  in  plants,  105 
Scales,  use  of,  in  measuring  absorp- 
tion, 103 

Season,  of  year,  effect  of  on  treat- 
ment, 40,  140 
Seasoning  timber,  necessity  for,  42 

effect  on  decay,  43 
checking,  43 
decreasing  freight,  43 
strength  of  wood,  224 

methods  used  in,  44 

in  hot  air,  46 

in  open  air,  44 

in  saturated  steam,  46 

in  superheated  steam,  47 

in  oil,  48 

in  water,  48 

ties,  197 

poles,  158 

mine  timbers,  189 

posts,  173 

cross  arms,  245 

piling,  182 

Seasoning  yards,  care  of,  45 
Seeley  process,  history  of,  12 

description  of,  54 
Shipworms,  description  of,  20 
Shingles,  woods  used  for,  205 

method  of  treating,  206 

treated  against  fire,  206 


INDEX 


311 


Shingles,  cost  of  treating,  207 
substitutes  for  wood,  247 

Shower  baths,  use  of  for  employees, 
104 

Shrinkage,  in  poles,  159 
equations  for,  226 

S-rons,  prevention  of  checking,  158 

Signals,  block,  use  of  treated  ties 
between,  241 

Silos,  treatment  of  wood  in,  209 

Slits,  effect  of,  in  cell  walls  upon 
penetration,  39 

Slipperiness,  in  wood  blocks,  200 

Smith,  C.  S.,  on  treatment  of  poles, 
163 

Sodium  carbonate,  as  a  fire  retard- 
ant,  216 

Sodium  fluoride,  its  value  as  a  pre- 
servative, 72,  253 

Sodium  silicate,  its  value  as  a  pre- 
servative, 252 

Soil,  effect  of  alkaline,  upon  wood, 
26,  221 

Specifications,  for  creosote,  261 
for  zinc  chloride,  73 

Spider  doors,  construction  of,  94 

Spikes,  kinds,  and  use  of,  143 
use  of  screw,  146 

Spirittine,  description  of,  252 

Springwood,  effect  on  penetration, 
34 

Square  sets,  treatment  of,  191 

Stains,  value  of,  in  preserving  wood, 
87 

Steel,  corrosion  of,  by  preservatives, 
68 

Steel  ties,  use  of,  243 

Steam,  seasoning  in  saturated,  46 
superheated,  47 

Steam  coils,  (see  coils) . 

Steaming,  effect  on  strength  of  wood, 
226 

Stone,  poles'setjn  crushed,  160 
posts  set  in  crushed,  174 

Streams,  pollution  of,  122 

Strength  of  wood  affected  by  seas- 
oning, 43,  224 
by  preservatives,  70,  230 
by  crude  oil,  231 


Strength  of  wood  affected  by  boil- 
ing, 229 

by  pressure,  232 
by  various  processes,  232 
by  temperature,  231 
zinc  chloride,  230 
steaming,  226 
of  ties,  144 
Storage  tanks,  use  and  construction 

of,  101 

Stubs,  used  for  reinforcing  poles,  164 
Substitutes,  for  treated  timber,  243 
Summerwood,  effect  of  on  penetra- 
tion, 34 


Tanks,  construction  of,  101 

Tars.,  classification  of,  77 

Teesdale,    C.    H.,    experiments    on 

penetration,  37 
on   absorption   of   creosote   by 

wood,  230 
Temperature,  effect  of  on  strength  of 

wood,  231 

Teredo,  description  of,  21 
Test  tracks,  need  for,  154 
Thermometer,  location  of  in  retort,  92 
Thinning  forests,  effect  of  wood  pre- 
servation on,  7 
Thilmany  process,  history  of,  13 

description  of,  249 
Tiemann,    H.    D.,    experiments    in 

penetration,  39 
effect  of  temperature  on  wood, 

231 

tests  on  strength  of  wood,, 224 
Tie  plates,  types  and  use  of,  141 
Ties,  selection  of  species  for,  128 
cost  of  treating,  150 
crushing  strength  of,  144 
durability  of,  303 
economy  in  treating,  151 
form  of,  131 
grouping,    to    secure    uniform 

treatment,  136 
hewn  vs.  sawed,  129 
length  of  time  to  season,  135 
peeling,  41 
sawed,  value  of,  129 


312 


INDEX 


Ties,  seasoning  of,  134 

selection  of  treating  process  for, 

148 
substitutes  for  wood,  243 

Tillson,  G.  W.,  studies  of  street 
pavements,  196 

Timber  supply,  effect  of  wood  pre- 
serving on,  2 

Timberasphalt,  description  of,   252 

Toxicity,  of  preservatives,  65 

Transfer  tables,  use  of,  99 

Track  scales,  use  of,  103 

Treated  timber,  amount  of  in  U.  S., 
259 

Turtles,  (see  anchors) 

Tyloses,  effect  of,  on  penetration,  35 

U 

United  States,  history  of  wood  pres- 
ervation in,  11 

Utilization,  of  top  logs,  caused  by 
wood  preservation,  8 

V 

Vacuum,  effect  of  in  treating  timber, 

107 

Vessels,  effect  of,  on  penetration,  35 
Volume,    of    charge,    difficulty    in 

measuring,  116 
Vulcanizing  process,  description  of, 

251 

W 

Waste,  in  hewing  ties,  130 
Water-gas-tar    creosote,    derivation 
and  composition  of,  85 

description  of,  253 

specification  for,  85 
Water-gas  tar,  (see  oil  tars) 
Water,  its  existence  in  wood,  43 

in  oil,  121 

soaking  wood  in,  48 
Wellhouse  process,  description  of,  62 
Winslow,  C.  P.,  on  creosotes,  75 
Winter,  effect  of,  on  cutting  timber 

in,  40 

Wood-block  paving,  oil  used  for,  84 
Wood  creosote,  description  of,  253 
Wood,  effect  of  water  in  on  strength, 
43 


Wood,  expansion  of  due  to  tempera- 
ture 120 

Wood    louse,    description    of     (see 
Limnoria) 

Wood  preservation,  definition  of,  1 

Wood  preserving  industry,   impor- 
tance of,  1 

Wood  preserving  plants,  list  of  in 

U.  S.,  255 
builders  of,  261 

Woodpeckers,   destruction  of  wood 
by,  27 

Wood  tars,  discussion  of,  79 

Wood  tar  creosote,  derivation  and 
composition  of,  86 

Working  tanks,  use  of,  101 

Wyoming  Experiment  Station,  tests 
on  posts,  175 


Xylotrya,  description  of,  20 
Y 

Yard,  arrangement  of,  99 
care  of,  45 
method  of  handling  timbers  in, 

100 
Yarborough,     R.     W.,    on    lagging 

retorts,  96 

Year,  effect  of  time  of,  on  treatment, 
40 

Z 

Zinc  chloride,  as  a  fire  retardant,  219 
changes  in  solutions,  122 
effect  upon  the  strength  of  wood, 

230 

its  value  as  a  preservative,  72 
manufacturers  of,  254 
method  of  analyzing,  297 

in  wood,  74 
specification  for,  73 
visual  tests  for,  74 
Zinc  chloride  process,  (see  Burnett 

process), 
Zinc  tannin  process,  (see  Wellhouse 

process) 

Zon,  R.,  on  the  manufacture  of  ties, 
130. 


YC  32988 


311744 


"7 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


